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Christensen DV, Steegemans TS, D Pomar T, Chen YZ, Smith A, Strocov VN, Kalisky B, Pryds N. Extreme magnetoresistance at high-mobility oxide heterointerfaces with dynamic defect tunability. Nat Commun 2024; 15:4249. [PMID: 38762504 PMCID: PMC11102559 DOI: 10.1038/s41467-024-48398-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 04/30/2024] [Indexed: 05/20/2024] Open
Abstract
Magnetic field-induced changes in the electrical resistance of materials reveal insights into the fundamental properties governing their electronic and magnetic behavior. Various classes of magnetoresistance have been realized, including giant, colossal, and extraordinary magnetoresistance, each with distinct physical origins. In recent years, extreme magnetoresistance (XMR) has been observed in topological and non-topological materials displaying a non-saturating magnetoresistance reaching 103-108% in magnetic fields up to 60 T. XMR is often intimately linked to a gapless band structure with steep bands and charge compensation. Here, we show that a linear XMR of 80,000% at 15 T and 2 K emerges at the high-mobility interface between the large band-gap oxides γ-Al2O3 and SrTiO3. Despite the chemically and electronically very dissimilar environment, the temperature/field phase diagrams of γ-Al2O3/SrTiO3 bear a striking resemblance to XMR semimetals. By comparing magnetotransport, microscopic current imaging, and momentum-resolved band structures, we conclude that the XMR in γ-Al2O3/SrTiO3 is not strongly linked to the band structure, but arises from weak disorder enforcing a squeezed guiding center motion of electrons. We also present a dynamic XMR self-enhancement through an autonomous redistribution of quasi-mobile oxygen vacancies. Our findings shed new light on XMR and introduce tunability using dynamic defect engineering.
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Affiliation(s)
- D V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark.
| | - T S Steegemans
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - T D Pomar
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - Y Z Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - A Smith
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland
| | - B Kalisky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - N Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark
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2
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Krieger JA, Stolz S, Robredo I, Manna K, McFarlane EC, Date M, Pal B, Yang J, B Guedes E, Dil JH, Polley CM, Leandersson M, Shekhar C, Borrmann H, Yang Q, Lin M, Strocov VN, Caputo M, Watson MD, Kim TK, Cacho C, Mazzola F, Fujii J, Vobornik I, Parkin SSP, Bradlyn B, Felser C, Vergniory MG, Schröter NBM. Weyl spin-momentum locking in a chiral topological semimetal. Nat Commun 2024; 15:3720. [PMID: 38697958 PMCID: PMC11066003 DOI: 10.1038/s41467-024-47976-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/17/2024] [Indexed: 05/05/2024] Open
Abstract
Spin-orbit coupling in noncentrosymmetric crystals leads to spin-momentum locking - a directional relationship between an electron's spin angular momentum and its linear momentum. Isotropic orthogonal Rashba spin-momentum locking has been studied for decades, while its counterpart, isotropic parallel Weyl spin-momentum locking has remained elusive in experiments. Theory predicts that Weyl spin-momentum locking can only be realized in structurally chiral cubic crystals in the vicinity of Kramers-Weyl or multifold fermions. Here, we use spin- and angle-resolved photoemission spectroscopy to evidence Weyl spin-momentum locking of multifold fermions in the chiral topological semimetal PtGa. We find that the electron spin of the Fermi arc surface states is orthogonal to their Fermi surface contour for momenta close to the projection of the bulk multifold fermion at the Γ point, which is consistent with Weyl spin-momentum locking of the latter. The direct measurement of the bulk spin texture of the multifold fermion at the R point also displays Weyl spin-momentum locking. The discovery of Weyl spin-momentum locking may lead to energy-efficient memory devices and Josephson diodes based on chiral topological semimetals.
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Affiliation(s)
- Jonas A Krieger
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232, Villigen PSI, Switzerland
| | - Samuel Stolz
- Department of Physics, University of California, Berkeley, CA, USA
- nanotech@surfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland
| | - Iñigo Robredo
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
- Donostia International Physics Center, 20018, Donostia - San Sebastian, Spain
| | - Kaustuv Manna
- Indian Institute of Technology-Delhi, Hauz Khas, New Delhi, 110 016, India
| | - Emily C McFarlane
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Mihir Date
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Banabir Pal
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Jiabao Yang
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Eduardo B Guedes
- Photon Science Division, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
- Institut de Physique, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - J Hugo Dil
- Photon Science Division, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
- Institut de Physique, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - Craig M Polley
- MAX IV Laboratory, Lund University, Fotongatan 2, 22484, Lund, Sweden
| | - Mats Leandersson
- MAX IV Laboratory, Lund University, Fotongatan 2, 22484, Lund, Sweden
| | - Chandra Shekhar
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Horst Borrmann
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Qun Yang
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Mao Lin
- Department of Physics, University of Illinois, Urbana-Champaign, USA
| | - Vladimir N Strocov
- Photon Science Division, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - Marco Caputo
- Photon Science Division, Paul Scherrer Institute, 5232, Villigen PSI, Switzerland
| | - Matthew D Watson
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Timur K Kim
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Cephise Cacho
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Federico Mazzola
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, I-34149, Italy
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, 30172, Venice, Italy
| | - Jun Fujii
- CNR-IOM, Area Science Park, Strada Statale 14 km 163.5, I-34149, Trieste, Italy
| | - Ivana Vobornik
- CNR-IOM, Area Science Park, Strada Statale 14 km 163.5, I-34149, Trieste, Italy
| | - Stuart S P Parkin
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Barry Bradlyn
- Department of Physics, University of Illinois, Urbana-Champaign, USA
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - Maia G Vergniory
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
- Donostia International Physics Center, 20018, Donostia - San Sebastian, Spain
| | - Niels B M Schröter
- Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany.
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3
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Düring PM, Rosenberger P, Baumgarten L, Alarab F, Lechermann F, Strocov VN, Müller M. Tunable 2D Electron- and 2D Hole States Observed at Fe/SrTiO 3 Interfaces. Adv Mater 2024; 36:e2309217. [PMID: 38245856 DOI: 10.1002/adma.202309217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 10/27/2023] [Indexed: 01/22/2024]
Abstract
Oxide electronics provide the key concepts and materials for enhancing silicon-based semiconductor technologies with novel functionalities. However, a basic but key property of semiconductor devices still needs to be unveiled in its oxidic counterparts: the ability to set or even switch between two types of carriers-either negatively (n) charged electrons or positively (p) charged holes. Here, direct evidence for individually emerging n- or p-type 2D band dispersions in STO-based heterostructures is provided using resonant photoelectron spectroscopy. The key to tuning the carrier character is the oxidation state of an adjacent Fe-based interface layer: For Fe and FeO, hole bands emerge in the empty bandgap region of STO due to hybridization of Ti- and Fe- derived states across the interface, while for Fe3O4 overlayers, an 2D electron system is formed. Unexpected oxygen vacancy characteristics arise for the hole-type interfaces, which as of yet had been exclusively assigned to the emergence of 2DESs. In general, this finding opens up the possibility to straightforwardly switch the type of conductivity at STO interfaces by the oxidation state of a redox overlayer. This will extend the spectrum of phenomena in oxide electronics, including the realization of combined n/p-type all-oxide transistors or logic gates.
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Affiliation(s)
- Pia M Düring
- Fachbereich Physik, Universität Konstanz, 78457, Konstanz, Germany
| | - Paul Rosenberger
- Fachbereich Physik, Universität Konstanz, 78457, Konstanz, Germany
- Fakultät Physik, Technische Universität Dortmund, 44221, Dortmund, Germany
| | - Lutz Baumgarten
- Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Fatima Alarab
- Paul Scherrer Institute, Swiss Light Source, Villingen PSI, CH-5232, Switzerland
| | - Frank Lechermann
- Institut für Theoretische Physik III, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Vladimir N Strocov
- Paul Scherrer Institute, Swiss Light Source, Villingen PSI, CH-5232, Switzerland
| | - Martina Müller
- Fachbereich Physik, Universität Konstanz, 78457, Konstanz, Germany
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4
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Reimers S, Odenbreit L, Šmejkal L, Strocov VN, Constantinou P, Hellenes AB, Jaeschke Ubiergo R, Campos WH, Bharadwaj VK, Chakraborty A, Denneulin T, Shi W, Dunin-Borkowski RE, Das S, Kläui M, Sinova J, Jourdan M. Direct observation of altermagnetic band splitting in CrSb thin films. Nat Commun 2024; 15:2116. [PMID: 38459058 PMCID: PMC10923844 DOI: 10.1038/s41467-024-46476-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 02/28/2024] [Indexed: 03/10/2024] Open
Abstract
Altermagnetism represents an emergent collinear magnetic phase with compensated order and an unconventional alternating even-parity wave spin order in the non-relativistic band structure. We investigate directly this unconventional band splitting near the Fermi energy through spin-integrated soft X-ray angular resolved photoemission spectroscopy. The experimentally obtained angle-dependent photoemission intensity, acquired from epitaxial thin films of the predicted altermagnet CrSb, demonstrates robust agreement with the corresponding band structure calculations. In particular, we observe the distinctive splitting of an electronic band on a low-symmetry path in the Brilliouin zone that connects two points featuring symmetry-induced degeneracy. The measured large magnitude of the spin splitting of approximately 0.6 eV and the position of the band just below the Fermi energy underscores the significance of altermagnets for spintronics based on robust broken time reversal symmetry responses arising from exchange energy scales, akin to ferromagnets, while remaining insensitive to external magnetic fields and possessing THz dynamics, akin to antiferromagnets.
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Affiliation(s)
- Sonka Reimers
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | - Lukas Odenbreit
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | - Libor Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
- Inst. of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, Praha 6, Czech Republic
| | | | | | - Anna B Hellenes
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | | | - Warlley H Campos
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | - Venkata K Bharadwaj
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | - Atasi Chakraborty
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
| | - Thibaud Denneulin
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Wen Shi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Suvadip Das
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Center for Quantum Science and Engineering, George Mason University, Fairfax, VA, 22030, USA
| | - Mathias Kläui
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
- Centre for Quantum Spintronics, Norwegian University of Science and Technology NTNU, 7491, Trondheim, Norway
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
- Department of Physics, Texas A&M University, College Station, TX, 77843-4242, USA
| | - Martin Jourdan
- Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany.
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5
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Liu R, Zhang W, Wei Y, Tao Z, Asmara TC, Li Y, Strocov VN, Yu R, Si Q, Schmitt T, Lu X. Nematic Spin Correlations Pervading the Phase Diagram of FeSe_{1-x}S_{x}. Phys Rev Lett 2024; 132:016501. [PMID: 38242670 DOI: 10.1103/physrevlett.132.016501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 12/08/2023] [Indexed: 01/21/2024]
Abstract
We use resonant inelastic x-ray scattering (RIXS) at the Fe-L_{3} edge to study the spin excitations of uniaxial-strained and unstrained FeSe_{1-x}S_{x} (0≤x≤0.21) samples. The measurements on unstrained samples reveal dispersive spin excitations in all doping levels, which show only minor doping dependence in energy dispersion, lifetime, and intensity, indicating that high-energy spin excitations are only marginally affected by sulfur doping. RIXS measurements on uniaxial-strained samples reveal that the high-energy spin-excitation anisotropy observed previously in FeSe is also present in the doping range 0200 K in x=0.18 and reaches a maximum around the nematic quantum critical doping (x_{c}≈0.17). Since the spin-excitation anisotropy directly reflects the existence of nematic spin correlations, our results indicate that high-energy nematic spin correlations pervade the regime of nematicity in the phase diagram and are enhanced by the nematic quantum criticality. These results emphasize the essential role of spin fluctuations in driving electronic nematicity and highlight the capability of uniaxial strain in tuning spin excitations in quantum materials hosting strong magnetoelastic coupling and electronic nematicity.
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Affiliation(s)
- Ruixian Liu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Wenliang Zhang
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Yuan Wei
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Zhen Tao
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Teguh C Asmara
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- European X-Ray Free-Electron Laser Facility GmbH, 22869 Schenefeld, Germany
| | - Yi Li
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Vladimir N Strocov
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Rong Yu
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Thorsten Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Xingye Lu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
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6
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Constantinou P, Stock TJZ, Crane E, Kölker A, van Loon M, Li J, Fearn S, Bornemann H, D'Anna N, Fisher AJ, Strocov VN, Aeppli G, Curson NJ, Schofield SR. Momentum-Space Imaging of Ultra-Thin Electron Liquids in δ-Doped Silicon. Adv Sci (Weinh) 2023; 10:e2302101. [PMID: 37469010 PMCID: PMC10520640 DOI: 10.1002/advs.202302101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 06/24/2023] [Indexed: 07/21/2023]
Abstract
Two-dimensional dopant layers (δ-layers) in semiconductors provide the high-mobility electron liquids (2DELs) needed for nanoscale quantum-electronic devices. Key parameters such as carrier densities, effective masses, and confinement thicknesses for 2DELs have traditionally been extracted from quantum magnetotransport. In principle, the parameters are immediately readable from the one-electron spectral function that can be measured by angle-resolved photoemission spectroscopy (ARPES). Here, buried 2DEL δ-layers in silicon are measured with soft X-ray (SX) ARPES to obtain detailed information about their filled conduction bands and extract device-relevant properties. This study takes advantage of the larger probing depth and photon energy range of SX-ARPES relative to vacuum ultraviolet (VUV) ARPES to accurately measure the δ-layer electronic confinement. The measurements are made on ambient-exposed samples and yield extremely thin (< 1 nm) and dense (≈1014 cm-2 ) 2DELs. Critically, this method is used to show that δ-layers of arsenic exhibit better electronic confinement than δ-layers of phosphorus fabricated under identical conditions.
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Affiliation(s)
- Procopios Constantinou
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
- Photon Science DivisionPaul Scherrer InstitutVilligen‐PSI5232Switzerland
| | - Taylor J. Z. Stock
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Eleanor Crane
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Alexander Kölker
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Marcel van Loon
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
| | - Juerong Li
- Advanced Technology InstituteUniversity of SurreyGuildfordGU2 7XHUK
| | - Sarah Fearn
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of MaterialsImperial College of LondonLondonSW7 2AZUK
| | - Henric Bornemann
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
| | - Nicolò D'Anna
- Photon Science DivisionPaul Scherrer InstitutVilligen‐PSI5232Switzerland
| | - Andrew J. Fisher
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
| | | | - Gabriel Aeppli
- Photon Science DivisionPaul Scherrer InstitutVilligen‐PSI5232Switzerland
- Institute of PhysicsEcole Polytechnique Fédérale de Lausanne (EPFL)Lausanne1015Switzerland
- Department of PhysicsETH ZürichZurich8093Switzerland
- Quantum CenterEidgenössische Technische Hochschule Zurich (ETHZ)Zurich8093Switzerland
| | - Neil J. Curson
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Electronic and Electrical EngineeringUniversity College LondonLondonWC1E 7JEUK
| | - Steven R. Schofield
- London Centre for NanotechnologyUniversity College LondonLondonWC1H 0AHUK
- Department of Physics and AstronomyUniversity College LondonLondonWC1E 6BTUK
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7
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Tam DW, Colonna N, Kumar N, Piamonteze C, Alarab F, Strocov VN, Cervellino A, Fennell T, Gawryluk DJ, Pomjakushina E, Soh Y, Kenzelmann M. Charge fluctuations in the intermediate-valence ground state of SmCoIn 5. Commun Phys 2023; 6:223. [PMID: 38665398 PMCID: PMC11041663 DOI: 10.1038/s42005-023-01339-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 08/08/2023] [Indexed: 04/28/2024]
Abstract
The microscopic mechanism of heavy band formation, relevant for unconventional superconductivity in CeCoIn5 and other Ce-based heavy fermion materials, depends strongly on the efficiency with which f electrons are delocalized from the rare earth sites and participate in a Kondo lattice. Replacing Ce3+ (4f1, J = 5/2) with Sm3+ (4f5, J = 5/2), we show that a combination of the crystal electric field and on-site Coulomb repulsion causes SmCoIn5 to exhibit a Γ7 ground state similar to CeCoIn5 with multiple f electrons. We show that with this single-ion ground state, SmCoIn5 exhibits a temperature-induced valence crossover consistent with a Kondo scenario, leading to increased delocalization of f holes below a temperature scale set by the crystal field, Tv ≈ 60 K. Our result provides evidence that in the case of many f electrons, the crystal field remains the dominant tuning knob in controlling the efficiency of delocalization near a heavy fermion quantum critical point, and additionally clarifies that charge fluctuations play a general role in the ground state of "115" materials.
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Affiliation(s)
- David W. Tam
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Nicola Colonna
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Neeraj Kumar
- Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Cinthia Piamonteze
- Photon Science Division, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Fatima Alarab
- Photon Science Division, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | | | - Antonio Cervellino
- Photon Science Division, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Tom Fennell
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Dariusz Jakub Gawryluk
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Ekaterina Pomjakushina
- Laboratory for Multiscale Materials Experiments, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Y. Soh
- Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Michel Kenzelmann
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
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8
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Strocov VN, Lev LL, Alarab F, Constantinou P, Wang X, Schmitt T, Stock TJZ, Nicolaï L, Očenášek J, Minár J. High-energy photoemission final states beyond the free-electron approximation. Nat Commun 2023; 14:4827. [PMID: 37563126 PMCID: PMC10415355 DOI: 10.1038/s41467-023-40432-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 07/26/2023] [Indexed: 08/12/2023] Open
Abstract
Three-dimensional (3D) electronic band structure is fundamental for understanding a vast diversity of physical phenomena in solid-state systems, including topological phases, interlayer interactions in van der Waals materials, dimensionality-driven phase transitions, etc. Interpretation of ARPES data in terms of 3D electron dispersions is commonly based on the free-electron approximation for the photoemission final states. Our soft-X-ray ARPES data on Ag metal reveals, however, that even at high excitation energies the final states can be a way more complex, incorporating several Bloch waves with different out-of-plane momenta. Such multiband final states manifest themselves as a complex structure and added broadening of the spectral peaks from 3D electron states. We analyse the origins of this phenomenon, and trace it to other materials such as Si and GaN. Our findings are essential for accurate determination of the 3D band structure over a wide range of materials and excitation energies in the ARPES experiment.
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Affiliation(s)
- V N Strocov
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland.
| | - L L Lev
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland
- Moscow Institute of Physics and Technology, 141701, Dolgoprudny, Russia
| | - F Alarab
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland
| | - P Constantinou
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland
| | - X Wang
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland
| | - T Schmitt
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen-PSI, Switzerland
| | - T J Z Stock
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
| | - L Nicolaï
- University of West Bohemia, New Technologies Research Centre, 301 00, Plzeň, Czech Republic
| | - J Očenášek
- University of West Bohemia, New Technologies Research Centre, 301 00, Plzeň, Czech Republic
| | - J Minár
- University of West Bohemia, New Technologies Research Centre, 301 00, Plzeň, Czech Republic.
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9
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Jardine MJA, Dardzinski D, Yu M, Purkayastha A, Chen AH, Chang YH, Engel A, Strocov VN, Hocevar M, Palmstrøm C, Frolov SM, Marom N. Correction to "First-Principles Assessment of CdTe as a Tunnel Barrier at the α-Sn/InSb Interface". ACS Appl Mater Interfaces 2023. [PMID: 37319365 DOI: 10.1021/acsami.3c07924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Affiliation(s)
- Malcolm J A Jardine
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Derek Dardzinski
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Maituo Yu
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Amrita Purkayastha
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - An-Hsi Chen
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - Yu-Hao Chang
- Materials Department, University of California-Santa Barbara, Santa Barbara, California 93106, United States
| | - Aaron Engel
- Materials Department, University of California-Santa Barbara, Santa Barbara, California 93106, United States
| | - Vladimir N Strocov
- Paul Scherrer Institut, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
| | - Moïra Hocevar
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France
| | - Chris Palmstrøm
- Materials Department, University of California-Santa Barbara, Santa Barbara, California 93106, United States
- Department of Electrical and Computer Engineering, University of California-Santa Barbara, Santa Barbara, California 93106, United States
| | - Sergey M Frolov
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Noa Marom
- Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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10
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Tseng Y, Paris E, Schmidt KP, Zhang W, Asmara TC, Bag R, Strocov VN, Singh S, Schlappa J, Rønnow HM, Schmitt T. Momentum-resolved spin-conserving two-triplon bound state and continuum in a cuprate ladder. Commun Phys 2023; 6:138. [PMID: 38665396 PMCID: PMC11041747 DOI: 10.1038/s42005-023-01250-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/23/2023] [Indexed: 04/28/2024]
Abstract
Studying multi-particle elementary excitations has provided unique access to understand collective many-body phenomena in correlated electronic materials, paving the way towards constructing microscopic models. In this work, we perform O K-edge resonant inelastic X-ray scattering (RIXS) on the quasi-one-dimensional cuprate Sr 14 Cu 24 O 41 with weakly-doped spin ladders. The RIXS signal is dominated by a dispersing sharp mode ~ 270 meV on top of a damped incoherent component ~ 400-500 meV. Comparing with model calculations using the perturbative continuous unitary transformations method, the two components resemble the spin-conserving ΔS = 0 two-triplon bound state and continuum excitations in the spin ladders. Such multi-spin response with long-lived ΔS = 0 excitons is central to several exotic magnetic properties featuring Majorana fermions, yet remains unexplored given the generally weak cross-section with other experimental techniques. By investigating a simple spin-ladder model system, our study provides valuable insight into low-dimensional quantum magnetism.
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Affiliation(s)
- Yi Tseng
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Present Address: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Eugenio Paris
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Kai P. Schmidt
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstraße 7, D-91058 Erlangen, Germany
| | - Wenliang Zhang
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Teguh Citra Asmara
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Rabindranath Bag
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008 India
- Present Address: Department of Physics, Duke University, Durham, NC 27708 USA
| | - Vladimir N. Strocov
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Surjeet Singh
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008 India
| | - Justine Schlappa
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
- European X-Ray Free-Electron Laser Facility GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Henrik M. Rønnow
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Thorsten Schmitt
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
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11
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Roychowdhury S, Yao M, Samanta K, Bae S, Chen D, Ju S, Raghavan A, Kumar N, Constantinou P, Guin SN, Plumb NC, Romanelli M, Borrmann H, Vergniory MG, Strocov VN, Madhavan V, Shekhar C, Felser C. Anomalous Hall Conductivity and Nernst Effect of the Ideal Weyl Semimetallic Ferromagnet EuCd 2 As 2. Adv Sci (Weinh) 2023; 10:e2207121. [PMID: 36828783 PMCID: PMC10161038 DOI: 10.1002/advs.202207121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/22/2023] [Indexed: 05/06/2023]
Abstract
Weyl semimetal is a unique topological phase with topologically protected band crossings in the bulk and robust surface states called Fermi arcs. Weyl nodes always appear in pairs with opposite chiralities, and they need to have either time-reversal or inversion symmetry broken. When the time-reversal symmetry is broken the minimum number of Weyl points (WPs) is two. If these WPs are located at the Fermi level, they form an ideal Weyl semimetal (WSM). In this study, intrinsic ferromagnetic (FM) EuCd2 As2 are grown, predicted to be an ideal WSM and studied its electronic structure by angle-resolved photoemission spectroscopy, and scanning tunneling microscopy which agrees closely with the first principles calculations. Moreover, anomalous Hall conductivity and Nernst effect are observed, resulting from the non-zero Berry curvature, and the topological Hall effect arising from changes in the band structure caused by spin canting produced by magnetic fields. These findings can help realize several exotic quantum phenomena in inorganic topological materials that are otherwise difficult to assess because of the presence of multiple pairs of Weyl nodes.
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Affiliation(s)
| | - Mengyu Yao
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Kartik Samanta
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Seokjin Bae
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana, Champaign, Urbana, IL, 61801, USA
| | - Dong Chen
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Sailong Ju
- Swiss Light Source, Paul Scherrer Institute, Villigen-PSI, CH-5232, Switzerland
| | - Arjun Raghavan
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana, Champaign, Urbana, IL, 61801, USA
| | - Nitesh Kumar
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
- S. N. Bose National Centre for Basic Sciences, Salt Lake City, Kolkata, 700 106, India
| | | | - Satya N Guin
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
- Department of Chemistry, Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Hyderabad, 500078, India
| | | | - Marisa Romanelli
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana, Champaign, Urbana, IL, 61801, USA
| | - Horst Borrmann
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Maia G Vergniory
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
- Donostia International Physics Center, Donostia-San Sebastian, 20018, Spain
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institute, Villigen-PSI, CH-5232, Switzerland
| | - Vidya Madhavan
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana, Champaign, Urbana, IL, 61801, USA
| | - Chandra Shekhar
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
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12
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Jardine MA, Dardzinski D, Yu M, Purkayastha A, Chen AH, Chang YH, Engel A, Strocov VN, Hocevar M, Palmstro̷m C, Frolov SM, Marom N. First-Principles Assessment of CdTe as a Tunnel Barrier at the α-Sn/InSb Interface. ACS Appl Mater Interfaces 2023; 15:16288-16298. [PMID: 36940162 PMCID: PMC10064317 DOI: 10.1021/acsami.3c00323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 03/09/2023] [Indexed: 06/17/2023]
Abstract
Majorana zero modes, with prospective applications in topological quantum computing, are expected to arise in superconductor/semiconductor interfaces, such as β-Sn and InSb. However, proximity to the superconductor may also adversely affect the semiconductor's local properties. A tunnel barrier inserted at the interface could resolve this issue. We assess the wide band gap semiconductor, CdTe, as a candidate material to mediate the coupling at the lattice-matched interface between α-Sn and InSb. To this end, we use density functional theory (DFT) with Hubbard U corrections, whose values are machine-learned via Bayesian optimization (BO) [ npj Computational Materials 2020, 6, 180]. The results of DFT+U(BO) are validated against angle resolved photoemission spectroscopy (ARPES) experiments for α-Sn and CdTe. For CdTe, the z-unfolding method [ Advanced Quantum Technologies 2022, 5, 2100033] is used to resolve the contributions of different kz values to the ARPES. We then study the band offsets and the penetration depth of metal-induced gap states (MIGS) in bilayer interfaces of InSb/α-Sn, InSb/CdTe, and CdTe/α-Sn, as well as in trilayer interfaces of InSb/CdTe/α-Sn with increasing thickness of CdTe. We find that 16 atomic layers (3.5 nm) of CdTe can serve as a tunnel barrier, effectively shielding the InSb from MIGS from the α-Sn. This may guide the choice of dimensions of the CdTe barrier to mediate the coupling in semiconductor-superconductor devices in future Majorana zero modes experiments.
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Affiliation(s)
- Malcolm
J. A. Jardine
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Derek Dardzinski
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Maituo Yu
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Amrita Purkayastha
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - An-Hsi Chen
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Yu-Hao Chang
- Université
Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble 38000, France
| | - Aaron Engel
- Université
Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble 38000, France
| | - Vladimir N. Strocov
- Materials
Department, University of California-Santa
Barbara, Santa
Barbara, California 93106, United States
| | - Moïra Hocevar
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Chris Palmstro̷m
- Université
Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble 38000, France
- Paul Scherrer
Institut, Swiss Light Source, Villigen PSI CH-5232, Switzerland
| | - Sergey M. Frolov
- Department
of Physics and Astronomy, University of
Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Noa Marom
- Department
of Materials Science and Engineering, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department
of Electrical and Computer Engineering, University of California-Santa Barbara, Santa Barbara, California 93106, United States
- Department
of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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13
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Cochran TA, Belopolski I, Manna K, Yahyavi M, Liu Y, Sanchez DS, Cheng ZJ, Yang XP, Multer D, Yin JX, Borrmann H, Chikina A, Krieger JA, Sánchez-Barriga J, Le Fèvre P, Bertran F, Strocov VN, Denlinger JD, Chang TR, Jia S, Felser C, Lin H, Chang G, Hasan MZ. Visualizing Higher-Fold Topology in Chiral Crystals. Phys Rev Lett 2023; 130:066402. [PMID: 36827563 DOI: 10.1103/physrevlett.130.066402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 01/18/2022] [Accepted: 12/14/2022] [Indexed: 06/18/2023]
Abstract
Novel topological phases of matter are fruitful platforms for the discovery of unconventional electromagnetic phenomena. Higher-fold topology is one example, where the low-energy description goes beyond standard model analogs. Despite intensive experimental studies, conclusive evidence remains elusive for the multigap topological nature of higher-fold chiral fermions. In this Letter, we leverage a combination of fine-tuned chemical engineering and photoemission spectroscopy with photon energy contrast to discover the higher-fold topology of a chiral crystal. We identify all bulk branches of a higher-fold chiral fermion for the first time, critically important for allowing us to explore unique Fermi arc surface states in multiple interband gaps, which exhibit an emergent ladder structure. Through designer chemical gating of the samples in combination with our measurements, we uncover an unprecedented multigap bulk boundary correspondence. Our demonstration of multigap electronic topology will propel future research on unconventional topological responses.
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Affiliation(s)
- Tyler A Cochran
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Kaustuv Manna
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Mohammad Yahyavi
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link 637371, Singapore
| | - Yiyuan Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Daniel S Sanchez
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Zi-Jia Cheng
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Xian P Yang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Daniel Multer
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Jia-Xin Yin
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Horst Borrmann
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Alla Chikina
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Jonas A Krieger
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, Switzerland
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Jaime Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein Strasse 15, 12489 Berlin, Germany
- IMDEA Nanoscience, C/ Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Patrick Le Fèvre
- SOLEIL Synchrotron, L'Orme des Merisiers, Départementale 128, F-91190 Saint-Aubin, France
| | - François Bertran
- SOLEIL Synchrotron, L'Orme des Merisiers, Départementale 128, F-91190 Saint-Aubin, France
| | | | - Jonathan D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Tay-Rong Chang
- Department of Physics, National Cheng Kung University, Tainan 70101, Taiwan
| | - Shuang Jia
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link 637371, Singapore
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Hsin Lin
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Guoqing Chang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link 637371, Singapore
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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14
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Popescu DG, Husanu MA, Constantinou PC, Filip LD, Trupina L, Bucur CI, Pasuk I, Chirila C, Hrib LM, Stancu V, Pintilie L, Schmitt T, Teodorescu CM, Strocov VN. Experimental Band Structure of Pb(Zr,Ti)O 3 : Mechanism of Ferroelectric Stabilization. Adv Sci (Weinh) 2023; 10:e2205476. [PMID: 36592417 PMCID: PMC9951575 DOI: 10.1002/advs.202205476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Pb(Zr,Ti)O3 (PZT) is the most common ferroelectric (FE) material widely used in solid-state technology. Despite intense studies of PZT over decades, its intrinsic band structure, electron energy depending on 3D momentum k, is still unknown. Here, Pb(Zr0.2 Ti0.8 )O3 using soft-X-ray angle-resolved photoelectron spectroscopy (ARPES) is explored. The enhanced photoelectron escape depth in this photon energy range allows sharp intrinsic definition of the out-of-plane momentum k and thereby of the full 3D band structure. Furthermore, the problem of sample charging due to the inherently insulating nature of PZT is solved by using thin-film PZT samples, where a thickness-induced self-doping results in their heavy doping. For the first time, the soft-X-ray ARPES experiments deliver the intrinsic 3D band structure of PZT as well as the FE-polarization dependent electrostatic potential profile across the PZT film deposited on SrTiO3 and Lax SrMn1- x O3 substrates. The negative charges near the surface, required to stabilize the FE state pointing away from the sample (P+), are identified as oxygen vacancies creating localized in-gap states below the Fermi energy. For the opposite polarization state (P-), the positive charges near the surface are identified as cation vacancies resulting from non-ideal stoichiometry of the PZT film as deduced from quantitative XPS measurements.
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Affiliation(s)
| | | | | | - Lucian Dragos Filip
- National Institute of Materials PhysicsAtomistilor 405AMagurele077125Romania
| | - Lucian Trupina
- National Institute of Materials PhysicsAtomistilor 405AMagurele077125Romania
| | | | - Iuliana Pasuk
- National Institute of Materials PhysicsAtomistilor 405AMagurele077125Romania
| | - Cristina Chirila
- National Institute of Materials PhysicsAtomistilor 405AMagurele077125Romania
| | | | - Viorica Stancu
- National Institute of Materials PhysicsAtomistilor 405AMagurele077125Romania
| | - Lucian Pintilie
- National Institute of Materials PhysicsAtomistilor 405AMagurele077125Romania
| | - Thorsten Schmitt
- Swiss Light SourcePaul Scherrer InstituteVilligen‐PSI5232Switzerland
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15
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Cheng ZJ, Belopolski I, Tien HJ, Cochran TA, Yang XP, Ma W, Yin JX, Chen D, Zhang J, Jozwiak C, Bostwick A, Rotenberg E, Cheng G, Hossain MS, Zhang Q, Litskevich M, Jiang YX, Yao N, Schroeter NBM, Strocov VN, Lian B, Felser C, Chang G, Jia S, Chang TR, Hasan MZ. Visualization of Tunable Weyl Line in A-A Stacking Kagome Magnets. Adv Mater 2023; 35:e2205927. [PMID: 36385535 DOI: 10.1002/adma.202205927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Kagome magnets provide a fascinating platform for a plethora of topological quantum phenomena, in which the delicate interplay between frustrated crystal structure, magnetization, and spin-orbit coupling (SOC) can engender highly tunable topological states. Here, utilizing angle-resolved photoemission spectroscopy, the Weyl lines are directly visualized with strong out-of-plane dispersion in the A-A stacked kagome magnet GdMn6 Sn6 . Remarkably, the Weyl lines exhibit a strong magnetization-direction-tunable SOC gap and binding energy tunability after substituting Gd with Tb and Li, respectively. These results not only illustrate the magnetization direction and valence counting as efficient tuning knobs for realizing and controlling distinct 3D topological phases, but also demonstrate AMn6 Sn6 (A = rare earth, or Li, Mg, or Ca) as a versatile material family for exploring diverse emergent topological quantum responses.
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Affiliation(s)
- Zi-Jia Cheng
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Hung-Ju Tien
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Tyler A Cochran
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Xian P Yang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Wenlong Ma
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Jia-Xin Yin
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Dong Chen
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Junyi Zhang
- Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Chris Jozwiak
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Guangming Cheng
- Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ, 08544, USA
| | - Md Shafayat Hossain
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Qi Zhang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Maksim Litskevich
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Yu-Xiao Jiang
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Nan Yao
- Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ, 08544, USA
| | | | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Biao Lian
- Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Guoqing Chang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871, China
| | - Tay-Rong Chang
- Department of Physics, National Cheng Kung University, Tainan, 70101, Taiwan
- Center for Quantum Frontiers of Research and Technology (QFort), Tainan, 701, Taiwan
- Physics Division, National Center for Theoretical Sciences, Taipei, 10617, Taiwan
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, 08544, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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16
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Belopolski I, Chang G, Cochran TA, Cheng ZJ, Yang XP, Hugelmeyer C, Manna K, Yin JX, Cheng G, Multer D, Litskevich M, Shumiya N, Zhang SS, Shekhar C, Schröter NBM, Chikina A, Polley C, Thiagarajan B, Leandersson M, Adell J, Huang SM, Yao N, Strocov VN, Felser C, Hasan MZ. Observation of a linked-loop quantum state in a topological magnet. Nature 2022; 604:647-652. [PMID: 35478239 DOI: 10.1038/s41586-022-04512-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 02/03/2022] [Indexed: 11/09/2022]
Abstract
Quantum phases can be classified by topological invariants, which take on discrete values capturing global information about the quantum state1-13. Over the past decades, these invariants have come to play a central role in describing matter, providing the foundation for understanding superfluids5, magnets6,7, the quantum Hall effect3,8, topological insulators9,10, Weyl semimetals11-13 and other phenomena. Here we report an unusual linking-number (knot theory) invariant associated with loops of electronic band crossings in a mirror-symmetric ferromagnet14-20. Using state-of-the-art spectroscopic methods, we directly observe three intertwined degeneracy loops in the material's three-torus, T3, bulk Brillouin zone. We find that each loop links each other loop twice. Through systematic spectroscopic investigation of this linked-loop quantum state, we explicitly draw its link diagram and conclude, in analogy with knot theory, that it exhibits the linking number (2, 2, 2), providing a direct determination of the invariant structure from the experimental data. We further predict and observe, on the surface of our samples, Seifert boundary states protected by the bulk linked loops, suggestive of a remarkable Seifert bulk-boundary correspondence. Our observation of a quantum loop link motivates the application of knot theory to the exploration of magnetic and superconducting quantum matter.
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Affiliation(s)
- Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA. .,RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama, Japan.
| | - Guoqing Chang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, Singapore
| | - Tyler A Cochran
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Zi-Jia Cheng
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Xian P Yang
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Cole Hugelmeyer
- Department of Mathematics, Princeton University, Princeton, NJ, USA
| | - Kaustuv Manna
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany.,Department of Physics, Indian Institute of Technology Delhi, New Delhi, India
| | - Jia-Xin Yin
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Guangming Cheng
- Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ, USA
| | - Daniel Multer
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Maksim Litskevich
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Nana Shumiya
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Songtian S Zhang
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA
| | - Chandra Shekhar
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | | | - Alla Chikina
- Swiss Light Source, Paul Scherrer Institut, Villigen, Switzerland
| | - Craig Polley
- MAX IV Laboratory, Lund University, Lund, Sweden
| | | | | | - Johan Adell
- MAX IV Laboratory, Lund University, Lund, Sweden
| | - Shin-Ming Huang
- Department of Physics, National Sun Yat-sen University, Kaohsiung City, Taiwan
| | - Nan Yao
- Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ, USA
| | | | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy, Department of Physics, Princeton University, Princeton, NJ, USA. .,Princeton Institute for Science and Technology of Materials, Princeton University, Princeton, NJ, USA. .,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. .,Quantum Science Center, Oak Ridge, TN, USA.
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17
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Kurzhals P, Kremer G, Jaouen T, Nicholson CW, Heid R, Nagel P, Castellan JP, Ivanov A, Muntwiler M, Rumo M, Salzmann B, Strocov VN, Reznik D, Monney C, Weber F. Electron-momentum dependence of electron-phonon coupling underlies dramatic phonon renormalization in YNi 2B 2C. Nat Commun 2022; 13:228. [PMID: 35017477 PMCID: PMC8752669 DOI: 10.1038/s41467-021-27843-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 12/16/2021] [Indexed: 11/09/2022] Open
Abstract
Electron-phonon coupling, i.e., the scattering of lattice vibrations by electrons and vice versa, is ubiquitous in solids and can lead to emergent ground states such as superconductivity and charge-density wave order. A broad spectral phonon line shape is often interpreted as a marker of strong electron-phonon coupling associated with Fermi surface nesting, i.e., parallel sections of the Fermi surface connected by the phonon momentum. Alternatively broad phonons are known to arise from strong atomic lattice anharmonicity. Here, we show that strong phonon broadening can occur in the absence of both Fermi surface nesting and lattice anharmonicity, if electron-phonon coupling is strongly enhanced for specific values of electron-momentum, k. We use inelastic neutron scattering, soft x-ray angle-resolved photoemission spectroscopy measurements and ab-initio lattice dynamical and electronic band structure calculations to demonstrate this scenario in the highly anisotropic tetragonal electron-phonon superconductor YNi2B2C. This new scenario likely applies to a wide range of compounds.
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Affiliation(s)
- Philipp Kurzhals
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
| | - Geoffroy Kremer
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700, Fribourg, Switzerland
| | - Thomas Jaouen
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700, Fribourg, Switzerland
- Univ Rennes, CNRS, IPR (Institut de Physique de Rennes) - UMR 6251, F-35000, Rennes, France
| | - Christopher W Nicholson
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700, Fribourg, Switzerland
| | - Rolf Heid
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
| | - Peter Nagel
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
| | - John-Paul Castellan
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
- Laboratoire Léon Brillouin (CEA-CNRS), CEA Saclay, F-91911, Gif-sur-Yvette, France
| | - Alexandre Ivanov
- Institut Laue-Langevin, 71 avenue des Martyrs CS 20156, 38042, Grenoble Cedex 9, France
| | - Matthias Muntwiler
- Paul Scherrer Institut, Swiss Light Source, 5232, Villigen PSI, Switzerland
| | - Maxime Rumo
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700, Fribourg, Switzerland
| | - Bjoern Salzmann
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700, Fribourg, Switzerland
| | - Vladimir N Strocov
- Paul Scherrer Institut, Swiss Light Source, 5232, Villigen PSI, Switzerland
| | - Dmitry Reznik
- Department of Physics, University of Colorado at Boulder, Boulder, CO, 80309, USA
- Center for Experiments on Quantum Materials, University of Colorado at Boulder, Boulder, CO, 80309, USA
| | - Claude Monney
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, 1700, Fribourg, Switzerland
| | - Frank Weber
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany.
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18
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Yu T, Wright J, Khalsa G, Pamuk B, Chang CS, Matveyev Y, Wang X, Schmitt T, Feng D, Muller DA, Xing HG, Jena D, Strocov VN. Momentum-resolved electronic structure and band offsets in an epitaxial NbN/GaN superconductor/semiconductor heterojunction. Sci Adv 2021; 7:eabi5833. [PMID: 34936435 PMCID: PMC8694612 DOI: 10.1126/sciadv.abi5833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 11/05/2021] [Indexed: 06/14/2023]
Abstract
The electronic structure of heterointerfaces is a pivotal factor for their device functionality. We use soft x-ray angle-resolved photoelectron spectroscopy to directly measure the momentum-resolved electronic band structures on both sides of the Schottky heterointerface formed by epitaxial films of the superconducting NbN on semiconducting GaN, and determine their momentum-dependent interfacial band offset as well as the band-bending profile. We find, in particular, that the Fermi states in NbN are well separated in energy and momentum from the states in GaN, excluding any notable electronic cross-talk of the superconducting states in NbN to GaN. We support the experimental findings with first-principles calculations for bulk NbN and GaN. The Schottky barrier height obtained from photoemission is corroborated by electronic transport and optical measurements. The momentum-resolved understanding of electronic properties of interfaces elucidated in our work opens up new frontiers for the quantum materials where interfacial states play a defining role.
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Affiliation(s)
- Tianlun Yu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - John Wright
- Materials Science and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Guru Khalsa
- Materials Science and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Betül Pamuk
- Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM), Cornell University, Ithaca, NY 14853, USA
| | - Celesta S. Chang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
| | - Yury Matveyev
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Xiaoqiang Wang
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Donglai Feng
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
- Hefei National Laboratory for Physical Science at Microscale, CAS Center for Excellence in Quantum Information and Quantum Physics, and Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - David A. Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
| | - Huili Grace Xing
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
- Electrical and Computer Engineering and Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Debdeep Jena
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
- Electrical and Computer Engineering and Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Vladimir N. Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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19
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He Y, Gayles J, Yao M, Helm T, Reimann T, Strocov VN, Schnelle W, Nicklas M, Sun Y, Fecher GH, Felser C. Large linear non-saturating magnetoresistance and high mobility in ferromagnetic MnBi. Nat Commun 2021; 12:4576. [PMID: 34321475 PMCID: PMC8319177 DOI: 10.1038/s41467-021-24692-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/01/2021] [Indexed: 11/21/2022] Open
Abstract
A large non-saturating magnetoresistance has been observed in several nonmagnetic topological Weyl semi-metals with high mobility of charge carriers at the Fermi energy. However, ferromagnetic systems rarely display a large magnetoresistance because of localized electrons in heavy d bands with a low Fermi velocity. Here, we report a large linear non-saturating magnetoresistance and high mobility in ferromagnetic MnBi. MnBi, unlike conventional ferromagnets, exhibits a large linear non-saturating magnetoresistance of 5000% under a pulsed field of 70 T. The electrons and holes' mobilities are both 5000 cm2V-1s-1 at 2 K, which are one of the highest for ferromagnetic materials. These phenomena are due to the spin-polarised Bi 6p band's sharp dispersion with a small effective mass. Our study provides an approach to achieve high mobility in ferromagnetic systems with a high Curie temperature, which is advantageous for topological spintronics.
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Affiliation(s)
- Yangkun He
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany.
| | - Jacob Gayles
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
- Department of Physics, University of South Florida, Tampa, FL, USA
| | - Mengyu Yao
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
| | - Toni Helm
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | - Tommy Reimann
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany
| | | | - Walter Schnelle
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
| | - Michael Nicklas
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
| | - Yan Sun
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
| | - Gerhard H Fecher
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
| | - Claudia Felser
- Max-Planck-Institute for Chemical Physics of Solids, Dresden, Germany
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20
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Chikina A, Christensen DV, Borisov V, Husanu MA, Chen Y, Wang X, Schmitt T, Radovic M, Nagaosa N, Mishchenko AS, Valentí R, Pryds N, Strocov VN. Band-Order Anomaly at the γ-Al 2O 3/SrTiO 3 Interface Drives the Electron-Mobility Boost. ACS Nano 2021; 15:4347-4356. [PMID: 33661601 DOI: 10.1021/acsnano.0c07609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite γ-Al2O3/SrTiO3 interface compared to the paradigm perovskite-perovskite LaAlO3/SrTiO3 interface. We explore the fundamental physics behind this phenomenon from direct measurements of the momentum-resolved electronic structure of this interface using resonant soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering of the mobile electrons in γ-Al2O3/SrTiO3 which depopulates electron states in the top SrTiO3 layer. This rearrangement of the mobile electron system pushes the electron density away from the interface, which reduces its overlap with the interfacial defects and weakens the electron-phonon interaction, both effects contributing to the mobility boost. A crystal-field analysis shows that the band order alters owing to the symmetry breaking between the spinel γ-Al2O3 and perovskite SrTiO3. Band-order engineering, exploiting the fundamental symmetry properties, emerges as another route to boost the performance of oxide devices.
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Affiliation(s)
- Alla Chikina
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
- Institute of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus, Denmark
| | - Dennis V Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Vladislav Borisov
- Institut für Theoretische Physik, Goethe-Universität Frankfurt am Main, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
- Department of Physics and Astronomy, Uppsala University, Box 516, 5120 Uppsala, Sweden
| | - Marius-Adrian Husanu
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoqiang Wang
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Milan Radovic
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
| | - Naoto Nagaosa
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Andrey S Mishchenko
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Roser Valentí
- Institut für Theoretische Physik, Goethe-Universität Frankfurt am Main, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
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21
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Elmers HJ, Chernov SV, D'Souza SW, Bommanaboyena SP, Bodnar SY, Medjanik K, Babenkov S, Fedchenko O, Vasilyev D, Agustsson SY, Schlueter C, Gloskovskii A, Matveyev Y, Strocov VN, Skourski Y, Šmejkal L, Sinova J, Minár J, Kläui M, Schönhense G, Jourdan M. Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn 2Au. ACS Nano 2020; 14:17554-17564. [PMID: 33236903 DOI: 10.1021/acsnano.0c08215] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Néel vector indicating the direction of the staggered magnetization. Pulsed magnetic fields of 60 T were used to orient the sublattice magnetizations of capped epitaxial Mn2Au(001) thin films perpendicular to the applied field direction by a spin-flop transition. The electronic structure and its corresponding changes were investigated by angular-resolved photoemission spectroscopy with photon energies in the vacuum-ultraviolet, soft, and hard X-ray range. The results reveal an energetic rearrangement of conduction electrons propagating perpendicular to the Néel vector. They confirm previous predictions on the origin of the Néel spin-orbit torque and anisotropic magnetoresistance in Mn2Au and reflect the combined antiferromagnetic and spin-orbit interaction in this compound leading to inversion symmetry breaking.
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Affiliation(s)
- H J Elmers
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S V Chernov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S W D'Souza
- New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - S P Bommanaboyena
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Yu Bodnar
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - K Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Babenkov
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - O Fedchenko
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - D Vasilyev
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - S Y Agustsson
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - C Schlueter
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - A Gloskovskii
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - Yu Matveyev
- Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI, Switzerland
| | - Y Skourski
- Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
| | - L Šmejkal
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - J Sinova
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
- Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic
| | - J Minár
- New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - M Kläui
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - G Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
| | - M Jourdan
- Institut für Physik, Johannes Gutenberg-Universität, Staudingerweg 7, D-55099 Mainz, Germany
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22
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Schröter NBM, Robredo I, Klemenz S, Kirby RJ, Krieger JA, Pei D, Yu T, Stolz S, Schmitt T, Dudin P, Kim TK, Cacho C, Schnyder A, Bergara A, Strocov VN, de Juan F, Vergniory MG, Schoop LM. Weyl fermions, Fermi arcs, and minority-spin carriers in ferromagnetic CoS 2. Sci Adv 2020; 6:6/51/eabd5000. [PMID: 33355138 DOI: 10.1126/sciadv.abd5000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.
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Affiliation(s)
- Niels B M Schröter
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
| | - Iñigo Robredo
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- Condensed Matter Physics Department, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
| | - Sebastian Klemenz
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
| | - Robert J Kirby
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA
| | - Jonas A Krieger
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zurich, CH-8093 Zurich, Switzerland
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Ding Pei
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Tianlun Yu
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Samuel Stolz
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Institute of Condensed Matter Physics, Station 3, EPFL, 1015 Lausanne, Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | | | | | | | - Andreas Schnyder
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - Aitor Bergara
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- Condensed Matter Physics Department, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain
- Centro de Física de Materiales, Centro Mixto CSIC -UPV/EHU, 20018 Donostia, Spain
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Fernando de Juan
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Maia G Vergniory
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain.
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Leslie M Schoop
- Department of Chemistry, Princeton University, Princeton, NJ 08540, USA.
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23
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Zhou JS, Reining L, Nicolaou A, Bendounan A, Ruotsalainen K, Vanzini M, Kas JJ, Rehr JJ, Muntwiler M, Strocov VN, Sirotti F, Gatti M. Unraveling intrinsic correlation effects with angle-resolved photoemission spectroscopy. Proc Natl Acad Sci U S A 2020; 117:28596-28602. [PMID: 33122434 PMCID: PMC7682325 DOI: 10.1073/pnas.2012625117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interaction effects can change materials properties in intriguing ways, and they have, in general, a huge impact on electronic spectra. In particular, satellites in photoemission spectra are pure many-body effects, and their study is of increasing interest in both experiment and theory. However, the intrinsic spectral function is only a part of a measured spectrum, and it is notoriously difficult to extract this information, even for simple metals. Our joint experimental and theoretical study of the prototypical simple metal aluminum demonstrates how intrinsic satellite spectra can be extracted from measured data using angular resolution in photoemission. A nondispersing satellite is detected and explained by electron-electron interactions and the thermal motion of the atoms. Additional nondispersing intensity comes from the inelastic scattering of the outgoing photoelectron. The ideal intrinsic spectral function, instead, has satellites that disperse both in energy and in shape. Theory and the information extracted from experiment describe these features with very good agreement.
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Affiliation(s)
- Jianqiang Sky Zhou
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA/DRF/IRAMIS, Institut Polytechnique de Paris, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility
- Sorbonne Université, CNRS, Institut des Nanosciences de Paris, UMR7588, F-75252 Paris, France
| | - Lucia Reining
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA/DRF/IRAMIS, Institut Polytechnique de Paris, F-91128 Palaiseau, France;
- European Theoretical Spectroscopy Facility
| | - Alessandro Nicolaou
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48 F-91192 Gif-sur-Yvette, France
| | - Azzedine Bendounan
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48 F-91192 Gif-sur-Yvette, France
| | - Kari Ruotsalainen
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48 F-91192 Gif-sur-Yvette, France
| | - Marco Vanzini
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA/DRF/IRAMIS, Institut Polytechnique de Paris, F-91128 Palaiseau, France
- European Theoretical Spectroscopy Facility
- Theory and Simulation of Materials, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - J J Kas
- Department of Physics, University of Washington, Seattle, WA 98195-1560
| | - J J Rehr
- Department of Physics, University of Washington, Seattle, WA 98195-1560
| | - Matthias Muntwiler
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Fausto Sirotti
- Laboratoire de Physique de la Matière Condensée, CNRS, École Polytechnique, Institut Polytechnique de Paris, F-91128 Palaiseau, France
| | - Matteo Gatti
- Laboratoire des Solides Irradiés, École Polytechnique, CNRS, CEA/DRF/IRAMIS, Institut Polytechnique de Paris, F-91128 Palaiseau, France;
- European Theoretical Spectroscopy Facility
- Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, BP 48 F-91192 Gif-sur-Yvette, France
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24
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Zhou KJ, Matsuyama S, Strocov VN. hv 2-concept breaks the photon-count limit of RIXS instrumentation. J Synchrotron Radiat 2020; 27:1235-1239. [PMID: 32876598 PMCID: PMC7467335 DOI: 10.1107/s1600577520008607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
Upon progressive refinement of energy resolution, the conventional resonant inelastic X-ray scattering (RIXS) instrumentation reaches the limit where the bandwidth of incident photons becomes insufficient to deliver an acceptable photon-count rate. Here it is shown that RIXS spectra as a function of energy loss are essentially invariant to their integration over incident energies within the core-hole lifetime. This fact permits RIXS instrumentation based on the hv2-concept to utilize incident synchrotron radiation over the whole core-hole lifetime window without any compromise on the much finer energy-loss resolution, thereby breaking the photon-count limit.
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Affiliation(s)
- Ke-Jin Zhou
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, United Kingdom
| | - Satoshi Matsuyama
- Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, Japan
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25
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Schröter NBM, Stolz S, Manna K, de Juan F, Vergniory MG, Krieger JA, Pei D, Schmitt T, Dudin P, Kim TK, Cacho C, Bradlyn B, Borrmann H, Schmidt M, Widmer R, Strocov VN, Felser C. Observation and control of maximal Chern numbers in a chiral topological semimetal. Science 2020; 369:179-183. [DOI: 10.1126/science.aaz3480] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 05/07/2020] [Indexed: 11/02/2022]
Abstract
Topological semimetals feature protected nodal band degeneracies characterized by a topological invariant known as the Chern number (C). Nodal band crossings with linear dispersion are expected to have at most |C|=4, which sets an upper limit to the magnitude of many topological phenomena in these materials. Here, we show that the chiral crystal palladium gallium (PdGa) displays multifold band crossings, which are connected by exactly four surface Fermi arcs, thus proving that they carry the maximal Chern number magnitude of 4. By comparing two enantiomers, we observe a reversal of their Fermi-arc velocities, which demonstrates that the handedness of chiral crystals can be used to control the sign of their Chern numbers.
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Affiliation(s)
| | - Samuel Stolz
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
- Institute of Condensed Matter Physics, Station 3, EPFL, 1015 Lausanne, Switzerland
| | - Kaustuv Manna
- Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany
| | - Fernando de Juan
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Maia G. Vergniory
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
- IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Jonas A. Krieger
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Ding Pei
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | | | | | | | - Barry Bradlyn
- Department of Physics and Institute for Condensed Matter Theory, University of Illinois at Urbana-Champaign, Urbana, IL 61801-3080, USA
| | - Horst Borrmann
- Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany
| | - Marcus Schmidt
- Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany
| | - Roland Widmer
- EMPA, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
| | - Vladimir N. Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany
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26
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Ma J, Wang H, Nie S, Yi C, Xu Y, Li H, Jandke J, Wulfhekel W, Huang Y, West D, Richard P, Chikina A, Strocov VN, Mesot J, Weng H, Zhang S, Shi Y, Qian T, Shi M, Ding H. Emergence of Nontrivial Low-Energy Dirac Fermions in Antiferromagnetic EuCd 2 As 2. Adv Mater 2020; 32:e1907565. [PMID: 32091144 DOI: 10.1002/adma.201907565] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/20/2020] [Indexed: 06/10/2023]
Abstract
Parity-time symmetry plays an essential role for the formation of Dirac states in Dirac semimetals. So far, all of the experimentally identified topologically nontrivial Dirac semimetals (DSMs) possess both parity and time reversal symmetry. The realization of magnetic topological DSMs remains a major issue in topological material research. Here, combining angle-resolved photoemission spectroscopy with density functional theory calculations, it is ascertained that band inversion induces a topologically nontrivial ground state in EuCd2 As2 . As a result, ideal magnetic Dirac fermions with simplest double cone structure near the Fermi level emerge in the antiferromagnetic (AFM) phase. The magnetic order breaks time reversal symmetry, but preserves inversion symmetry. The double degeneracy of the Dirac bands is protected by a combination of inversion, time-reversal, and an additional translation operation. Moreover, the calculations show that a deviation of the magnetic moments from the c-axis leads to the breaking of C3 rotation symmetry, and thus, a small bandgap opens at the Dirac point in the bulk. In this case, the system hosts a novel state containing three different types of topological insulator: axion insulator, AFM topological crystalline insulator (TCI), and higher order topological insulator. The results provide an enlarged platform for the quest of topological Dirac fermions in a magnetic system.
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Affiliation(s)
- Junzhang Ma
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen, PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15, Lausanne, Switzerland
| | - Han Wang
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Simin Nie
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Changjiang Yi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Yuanfeng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Hang Li
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Jasmin Jandke
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen, PSI, Switzerland
| | - Wulf Wulfhekel
- Physikalisches Institut, Karlsruhe Institute of Technology, 76131, Karlsruhe, Germany
| | - Yaobo Huang
- Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201204, China
| | - Damien West
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Pierre Richard
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing, 100190, China
- Institut quantique, Université de Sherbrooke, 2500 boulevard de l'Université, Sherbrooke, Québec, J1K 2R1, Canada
| | - Alla Chikina
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen, PSI, Switzerland
| | - Vladimir N Strocov
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen, PSI, Switzerland
| | - Joël Mesot
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen, PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, CH-10 15, Lausanne, Switzerland
| | - Hongming Weng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory Dongguan, Guangdong, 523808, China
| | - Shengbai Zhang
- Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Youguo Shi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory Dongguan, Guangdong, 523808, China
| | - Tian Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory Dongguan, Guangdong, 523808, China
| | - Ming Shi
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen, PSI, Switzerland
| | - Hong Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing, 100190, China
- Songshan Lake Materials Laboratory Dongguan, Guangdong, 523808, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, 100190, China
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27
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Kumar N, Yao M, Nayak J, Vergniory MG, Bannies J, Wang Z, Schröter NBM, Strocov VN, Müchler L, Shi W, Rienks EDL, Mañes JL, Shekhar C, Parkin SSP, Fink J, Fecher GH, Sun Y, Bernevig BA, Felser C. Signatures of Sixfold Degenerate Exotic Fermions in a Superconducting Metal PdSb 2. Adv Mater 2020; 32:e1906046. [PMID: 32037624 DOI: 10.1002/adma.201906046] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 12/24/2019] [Indexed: 06/10/2023]
Abstract
Multifold degenerate points in the electronic structure of metals lead to exotic behaviors. These range from twofold and fourfold degenerate Weyl and Dirac points, respectively, to sixfold and eightfold degenerate points that are predicted to give rise, under modest magnetic fields or strain, to topological semimetallic behaviors. The present study shows that the nonsymmorphic compound PdSb2 hosts six-component fermions or sextuplets. Using angle-resolved photoemission spectroscopy, crossing points formed by three twofold degenerate parabolic bands are directly observed at the corner of the Brillouin zone. The group theory analysis proves that under weak spin-orbit interaction, a band inversion occurs.
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Affiliation(s)
- Nitesh Kumar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Mengyu Yao
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Jayita Nayak
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Maia G Vergniory
- Donostian International Physics Center, Paseo Manuel de Lardizabal 4, 20018, San Sebastian, Spain
- KERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao, Spain
| | - Jörn Bannies
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Zhijun Wang
- Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | | | | | - Lukas Müchler
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
- Center for Computational Quantum Physics, The Flatiron Institute, New York, NY, 10010, USA
| | - Wujun Shi
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Emile D L Rienks
- Leibniz Institut für Festkörper und Werkstoffforschung IFW Dresden, Helmholtzstrasse 20, 01171, Dresden, Germany
- Institute of Solid State Physics, Dresden University of Technology, Zellescher Weg 16, 01062, Dresden, Germany
| | - J L Mañes
- Condensed Matter Physics Department, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Apdo. 644, 48080, Bilbao, Spain
| | - Chandra Shekhar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, 06120, Halle, Germany
| | - Jörg Fink
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
- Leibniz Institut für Festkörper und Werkstoffforschung IFW Dresden, Helmholtzstrasse 20, 01171, Dresden, Germany
- Institute of Solid State Physics, Dresden University of Technology, Zellescher Weg 16, 01062, Dresden, Germany
| | - Gerhard H Fecher
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - Yan Sun
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
| | - B Andrei Bernevig
- Department of Physics, Princeton University, Princeton, NJ, 08544, USA
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187, Dresden, Germany
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28
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Liu Y, Luchini A, Martí-Sánchez S, Koch C, Schuwalow S, Khan SA, Stankevič T, Francoual S, Mardegan JRL, Krieger JA, Strocov VN, Stahn J, Vaz CAF, Ramakrishnan M, Staub U, Lefmann K, Aeppli G, Arbiol J, Krogstrup P. Coherent Epitaxial Semiconductor-Ferromagnetic Insulator InAs/EuS Interfaces: Band Alignment and Magnetic Structure. ACS Appl Mater Interfaces 2020; 12:8780-8787. [PMID: 31877013 DOI: 10.1021/acsami.9b15034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hybrid semiconductor-ferromagnetic insulator heterostructures are interesting due to their tunable electronic transport, self-sustained stray field, and local proximitized magnetic exchange. In this work, we present lattice-matched hybrid epitaxy of semiconductor-ferromagnetic insulator InAs/EuS heterostructures and analyze the atomic-scale structure and their electronic and magnetic characteristics. The Fermi level at the InAs/EuS interface is found to be close to the InAs conduction band and in the band gap of EuS, thus preserving the semiconducting properties. Both neutron and X-ray reflectivity measurements show that the overall ferromagnetic component is mainly localized in the EuS thin film with a suppression of the Eu moment in the EuS layer nearest the InAs and magnetic moments outside the detection limits on the pure InAs side. This work presents a step toward realizing defect-free semiconductor-ferromagnetic insulator epitaxial hybrids for spin-lifted quantum and spintronic applications without external magnetic fields.
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Affiliation(s)
- Yu Liu
- Microsoft Quantum Materials Lab Copenhagen , 2800 Lyngby , Denmark
| | | | - Sara Martí-Sánchez
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Catalonia , Spain
| | - Christian Koch
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Catalonia , Spain
| | - Sergej Schuwalow
- Microsoft Quantum Materials Lab Copenhagen , 2800 Lyngby , Denmark
| | - Sabbir A Khan
- Microsoft Quantum Materials Lab Copenhagen , 2800 Lyngby , Denmark
| | - Tomaš Stankevič
- Microsoft Quantum Materials Lab Copenhagen , 2800 Lyngby , Denmark
| | - Sonia Francoual
- Deutsches Elektronen-Synchrotron DESY , Hamburg 22603 , Germany
| | | | | | | | - Jochen Stahn
- Paul Scherrer Institute , CH-5232 Villigen , Switzerland
| | - Carlos A F Vaz
- Paul Scherrer Institute , CH-5232 Villigen , Switzerland
| | | | - Urs Staub
- Paul Scherrer Institute , CH-5232 Villigen , Switzerland
| | | | - Gabriel Aeppli
- Paul Scherrer Institute , CH-5232 Villigen , Switzerland
- ETH , CH-8093 Zürich , Switzerland
- EPFL , CH-1015 Lausanne , Switzerland
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST , Campus UAB, Bellaterra , 08193 Barcelona , Catalonia , Spain
- ICREA , Pg. Lluís Companys 23 , 08010 Barcelona , Catalonia , Spain
| | - Peter Krogstrup
- Microsoft Quantum Materials Lab Copenhagen , 2800 Lyngby , Denmark
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29
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Arab A, Liu X, Köksal O, Yang W, Chandrasena RU, Middey S, Kareev M, Kumar S, Husanu MA, Yang Z, Gu L, Strocov VN, Lee TL, Minár J, Pentcheva R, Chakhalian J, Gray AX. Electronic Structure of a Graphene-like Artificial Crystal of NdNiO 3. Nano Lett 2019; 19:8311-8317. [PMID: 31644875 DOI: 10.1021/acs.nanolett.9b03962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Artificial complex-oxide heterostructures containing ultrathin buried layers grown along the pseudocubic [111] direction have been predicted to host a plethora of exotic quantum states arising from the graphene-like lattice geometry and the interplay between strong electronic correlations and band topology. To date, however, electronic-structural investigations of such atomic layers remain an immense challenge due to the shortcomings of conventional surface-sensitive probes with typical information depths of a few angstroms. Here, we use a combination of bulk-sensitive soft X-ray angle-resolved photoelectron spectroscopy (SX-ARPES), hard X-ray photoelectron spectroscopy (HAXPES), and state-of-the-art first-principles calculations to demonstrate a direct and robust method for extracting momentum-resolved and angle-integrated valence-band electronic structure of an ultrathin buckled graphene-like layer of NdNiO3 confined between two 4-unit cell-thick layers of insulating LaAlO3. The momentum-resolved dispersion of the buried Ni d states near the Fermi level obtained via SX-ARPES is in excellent agreement with the first-principles calculations and establishes the realization of an antiferro-orbital order in this artificial lattice. The HAXPES measurements reveal the presence of a valence-band bandgap of 265 meV. Our findings open a promising avenue for designing and investigating quantum states of matter with exotic order and topology in a few buried layers.
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Affiliation(s)
- Arian Arab
- Department of Physics , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Xiaoran Liu
- Department of Physics and Astronomy , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Okan Köksal
- Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE) , University of Duisburg-Essen , Duisburg 47057 , Germany
| | - Weibing Yang
- Department of Physics , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Ravini U Chandrasena
- Department of Physics , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Srimanta Middey
- Department of Physics , Indian Institute of Science , Bengaluru 560 012 , India
| | - Mikhail Kareev
- Department of Physics and Astronomy , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Siddharth Kumar
- Department of Physics , Indian Institute of Science , Bengaluru 560 012 , India
| | - Marius-Adrian Husanu
- Swiss Light Source , Paul Scherrer Institute , 5232 Villigen , Switzerland
- National Institute of Materials Physics , 077125 Atomistilor 405A , Magurele , Romania
| | - Zhenzhong Yang
- Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , People's Republic of China
| | - Lin Gu
- Beijing National Laboratory for Condensed-Matter Physics and Institute of Physics , Chinese Academy of Sciences , Beijing 100190 , People's Republic of China
- Collaborative Innovation Center of Quantum Matter , Beijing 100190 , People's Republic of China
| | - Vladimir N Strocov
- Swiss Light Source , Paul Scherrer Institute , 5232 Villigen , Switzerland
| | - Tien-Lin Lee
- Diamond Light Source Ltd. , Didcot, Oxfordshire OX11 0DE , United Kingdom
| | - Jan Minár
- New Technologies-Research Center , University of West Bohemia , CZ-30614 Pilsen , Czech Republic
| | - Rossitza Pentcheva
- Department of Physics and Center for Nanointegration Duisburg-Essen (CENIDE) , University of Duisburg-Essen , Duisburg 47057 , Germany
| | - Jak Chakhalian
- Department of Physics and Astronomy , Rutgers University , Piscataway , New Jersey 08854 , United States
| | - Alexander X Gray
- Department of Physics , Temple University , Philadelphia , Pennsylvania 19122 , United States
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30
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Yao MY, Xu N, Wu QS, Autès G, Kumar N, Strocov VN, Plumb NC, Radovic M, Yazyev OV, Felser C, Mesot J, Shi M. Observation of Weyl Nodes in Robust Type-II Weyl Semimetal WP_{2}. Phys Rev Lett 2019; 122:176402. [PMID: 31107063 DOI: 10.1103/physrevlett.122.176402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Indexed: 06/09/2023]
Abstract
Distinct to type-I Weyl semimetals (WSMs) that host quasiparticles described by the Weyl equation, the energy dispersion of quasiparticles in type-II WSMs violates Lorentz invariance and the Weyl cones in the momentum space are tilted. Since it was proposed that type-II Weyl fermions could emerge from (W,Mo)Te_{2} and (W,Mo)P_{2} families of materials, a large number of experiments have been dedicated to unveiling the possible manifestation of type-II WSMs, e.g., surface-state Fermi arcs. However, the interpretations of the experimental results are very controversial. Here, using angle-resolved photoemission spectroscopy supported by the first-principles calculations, we probe the tilted Weyl cone bands in the bulk electronic structure of WP_{2} directly, which are at the origin of Fermi arcs at the surfaces and transport properties related to the chiral anomaly in type-II WSMs. Our results ascertain that, due to the spin-orbit coupling, the Weyl nodes originate from the splitting of fourfold degenerate band-crossing points with Chern numbers C=±2 induced by the crystal symmetries of WP_{2}, which is unique among all the discovered WSMs. Our finding also provides a guiding line to observe the chiral anomaly that could manifest in novel transport properties.
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Affiliation(s)
- M-Y Yao
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Q S Wu
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - G Autès
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - N Kumar
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - O V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - C Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
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31
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Schlappa J, Kumar U, Zhou KJ, Singh S, Mourigal M, Strocov VN, Revcolevschi A, Patthey L, Rønnow HM, Johnston S, Schmitt T. Probing multi-spinon excitations outside of the two-spinon continuum in the antiferromagnetic spin chain cuprate Sr 2CuO 3. Nat Commun 2018; 9:5394. [PMID: 30568161 PMCID: PMC6300594 DOI: 10.1038/s41467-018-07838-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 11/26/2018] [Indexed: 11/09/2022] Open
Abstract
One-dimensional (1D) magnetic insulators have attracted significant interest as a platform for studying quasiparticle fractionalization, quantum criticality, and emergent phenomena. The spin-1/2 Heisenberg chain with antiferromagnetic nearest neighbour interactions is an important reference system; its elementary magnetic excitations are spin-1/2 quasiparticles called spinons that are created in even numbers. However, while the excitation continuum associated with two-spinon states is routinely observed, the study of four-spinon and higher multi-spinon states is an open area of research. Here we show that four-spinon excitations can be accessed directly in Sr2CuO3 using resonant inelastic x-ray scattering (RIXS) in a region of phase space clearly separated from the two-spinon continuum. Our finding is made possible by the fundamental differences in the correlation function probed by RIXS in comparison to other probes. This advance holds promise as a tool in the search for novel quantum states and quantum spin liquids.
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Affiliation(s)
- J Schlappa
- European X-Ray Free-Electron Laser Facility GmbH, Holzkoppel 4, 22869, Schenefeld, Germany.
- Photon Science Division, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.
| | - U Kumar
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, 37996, USA
| | - K J Zhou
- Photon Science Division, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - S Singh
- Department of Physics, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, 411008, India
| | - M Mourigal
- École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
- School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - V N Strocov
- Photon Science Division, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - A Revcolevschi
- Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Sud 11, UMR 8182, 91405, Orsay, France
| | - L Patthey
- Photon Science Division, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland
| | - H M Rønnow
- École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland
| | - S Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, TN, 37996, USA.
| | - T Schmitt
- Photon Science Division, Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.
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32
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Xu N, Wang ZW, Magrez A, Bugnon P, Berger H, Matt CE, Strocov VN, Plumb NC, Radovic M, Pomjakushina E, Conder K, Dil JH, Mesot J, Yu R, Ding H, Shi M. Evidence of a Coulomb-Interaction-Induced Lifshitz Transition and Robust Hybrid Weyl Semimetal in T_{d}-MoTe_{2}. Phys Rev Lett 2018; 121:136401. [PMID: 30312078 DOI: 10.1103/physrevlett.121.136401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/16/2018] [Indexed: 06/08/2023]
Abstract
Using soft x-ray angle-resolved photoemission spectroscopy we probed the bulk electronic structure of T_{d}-MoTe_{2}. We found that on-site Coulomb interaction leads to a Lifshitz transition, which is essential for a precise description of the electronic structure. A hybrid Weyl semimetal state with a pair of energy bands touching at both type-I and type-II Weyl nodes is indicated by comparing the experimental data with theoretical calculations. Unveiling the importance of Coulomb interaction opens up a new route to comprehend the unique properties of MoTe_{2}, and is significant for understanding the interplay between correlation effects, strong spin-orbit coupling and superconductivity in this van der Waals material.
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Affiliation(s)
- N Xu
- Institute of Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Z W Wang
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - A Magrez
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - P Bugnon
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - H Berger
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - J H Dil
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - R Yu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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33
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Chikina A, Lechermann F, Husanu MA, Caputo M, Cancellieri C, Wang X, Schmitt T, Radovic M, Strocov VN. Orbital Ordering of the Mobile and Localized Electrons at Oxygen-Deficient LaAlO 3/SrTiO 3 Interfaces. ACS Nano 2018; 12:7927-7935. [PMID: 29995384 DOI: 10.1021/acsnano.8b02335] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Interfacing different transition-metal oxides opens a route to functionalizing their rich interplay of electron, spin, orbital, and lattice degrees of freedom for electronic and spintronic devices. Electronic and magnetic properties of SrTiO3-based interfaces hosting a mobile two-dimensional electron system (2DES) are strongly influenced by oxygen vacancies, which form an electronic dichotomy, where strongly correlated localized electrons in the in-gap states (IGSs) coexist with noncorrelated delocalized 2DES. Here, we use resonant soft-X-ray photoelectron spectroscopy to prove the eg character of the IGSs, as opposed to the t2g character of the 2DES in the paradigmatic LaAlO3/SrTiO3 interface. We furthermore separate the d xy and d xz/d xz orbital contributions based on deeper consideration of the resonant photoexcitation process in terms of orbital and momentum selectivity. Supported by a self-consistent combination of density functional theory and dynamical mean field theory calculations, this experiment identifies local orbital reconstruction that goes beyond the conventional eg- vs-t2g band ordering. A hallmark of oxygen-deficient LaAlO3/SrTiO3 is a significant hybridization of the eg and t2g orbitals. Our findings provide routes for tuning the electronic and magnetic properties of oxide interfaces through "defect engineering" with oxygen vacancies.
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Affiliation(s)
- Alla Chikina
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
| | - Frank Lechermann
- Institut für Theoretische Physik , Universität Hamburg , Jungiusstrasse 9 , Hamburg DE-20355 , Germany
| | - Marius-Adrian Husanu
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
- National Institute of Materials Physics , Atomistilor 405A , Magurele RO-077125 , Romania
| | - Marco Caputo
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
| | - Claudia Cancellieri
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
- Empa, Swiss Federal Laboratories for Materials Science & Technology , Ueberlandstrasse 129 , Duebendorf CH-8600 , Switzerland
| | - Xiaoqiang Wang
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
| | - Milan Radovic
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institute , Villigen CH-5232 , Switzerland
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34
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Horio M, Hauser K, Sassa Y, Mingazheva Z, Sutter D, Kramer K, Cook A, Nocerino E, Forslund OK, Tjernberg O, Kobayashi M, Chikina A, Schröter NBM, Krieger JA, Schmitt T, Strocov VN, Pyon S, Takayama T, Takagi H, Lipscombe OJ, Hayden SM, Ishikado M, Eisaki H, Neupert T, Månsson M, Matt CE, Chang J. Three-Dimensional Fermi Surface of Overdoped La-Based Cuprates. Phys Rev Lett 2018; 121:077004. [PMID: 30169083 DOI: 10.1103/physrevlett.121.077004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Indexed: 06/08/2023]
Abstract
We present a soft x-ray angle-resolved photoemission spectroscopy study of overdoped high-temperature superconductors. In-plane and out-of-plane components of the Fermi surface are mapped by varying the photoemission angle and the incident photon energy. No k_{z} dispersion is observed along the nodal direction, whereas a significant antinodal k_{z} dispersion is identified for La-based cuprates. Based on a tight-binding parametrization, we discuss the implications for the density of states near the van Hove singularity. Our results suggest that the large electronic specific heat found in overdoped La_{2-x}Sr_{x}CuO_{4} cannot be assigned to the van Hove singularity alone. We therefore propose quantum criticality induced by a collapsing pseudogap phase as a plausible explanation for observed enhancement of electronic specific heat.
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Affiliation(s)
- M Horio
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - K Hauser
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Y Sassa
- Department of Physics and Astronomy, Uppsala University, SE-75121 Uppsala, Sweden
| | - Z Mingazheva
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - D Sutter
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - K Kramer
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - A Cook
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - E Nocerino
- Department of Applied Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Stockholm Kista, Sweden
| | - O K Forslund
- Department of Applied Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Stockholm Kista, Sweden
| | - O Tjernberg
- Department of Applied Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Stockholm Kista, Sweden
| | - M Kobayashi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - A Chikina
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - N B M Schröter
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J A Krieger
- Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich, Switzerland
| | - T Schmitt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - S Pyon
- Department of Advanced Materials, University of Tokyo, Kashiwa 277-8561, Japan
| | - T Takayama
- Department of Advanced Materials, University of Tokyo, Kashiwa 277-8561, Japan
| | - H Takagi
- Department of Advanced Materials, University of Tokyo, Kashiwa 277-8561, Japan
| | - O J Lipscombe
- H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - S M Hayden
- H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, United Kingdom
| | - M Ishikado
- Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan
| | - H Eisaki
- Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8568, Japan
| | - T Neupert
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - M Månsson
- Department of Applied Physics, KTH Royal Institute of Technology, Electrum 229, SE-16440 Stockholm Kista, Sweden
| | - C E Matt
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - J Chang
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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35
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Kormondy KJ, Gao L, Li X, Lu S, Posadas AB, Shen S, Tsoi M, McCartney MR, Smith DJ, Zhou J, Lev LL, Husanu MA, Strocov VN, Demkov AA. Large positive linear magnetoresistance in the two-dimensional t 2g electron gas at the EuO/SrTiO 3 interface. Sci Rep 2018; 8:7721. [PMID: 29769572 PMCID: PMC5955958 DOI: 10.1038/s41598-018-26017-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 05/03/2018] [Indexed: 11/09/2022] Open
Abstract
The development of novel nano-oxide spintronic devices would benefit greatly from interfacing with emergent phenomena at oxide interfaces. In this paper, we integrate highly spin-split ferromagnetic semiconductor EuO onto perovskite SrTiO3 (001). A careful deposition of Eu metal by molecular beam epitaxy results in EuO growth via oxygen out-diffusion from SrTiO3. This in turn leaves behind a highly conductive interfacial layer through generation of oxygen vacancies. Below the Curie temperature of 70 K of EuO, this spin-polarized two-dimensional t 2g electron gas at the EuO/SrTiO3 interface displays very large positive linear magnetoresistance (MR). Soft x-ray angle-resolved photoemission spectroscopy (SX-ARPES) reveals the t 2g nature of the carriers. First principles calculations strongly suggest that Zeeman splitting, caused by proximity magnetism and oxygen vacancies in SrTiO3, is responsible for the MR. This system offers an as-yet-unexplored route to pursue proximity-induced effects in the oxide two-dimensional t 2g electron gas.
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Affiliation(s)
- Kristy J Kormondy
- Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Lingyuan Gao
- Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Xiang Li
- Materials Science and Engineering Program/Mechanical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Sirong Lu
- School of Engineering for Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA
| | - Agham B Posadas
- Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Shida Shen
- Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Maxim Tsoi
- Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA
| | - Martha R McCartney
- Department of Physics, Arizona State University, Tempe, Arizona, 85287, USA
| | - David J Smith
- Department of Physics, Arizona State University, Tempe, Arizona, 85287, USA
| | - Jianshi Zhou
- Materials Science and Engineering Program/Mechanical Engineering, University of Texas at Austin, Austin, Texas, 78712, USA
| | - Leonid L Lev
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen PSI, Switzerland.,National Research Centre "Kurchatov Institute", 1 Akademika Kurchatova pl., 123182, Moscow, Russia
| | - Marius-Adrian Husanu
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen PSI, Switzerland.,National Institute of Materials Physics, 405A Atomistilor Str., 077125, Magurele, Romania
| | - Vladimir N Strocov
- Paul Scherrer Institute, Swiss Light Source, CH-5232, Villigen PSI, Switzerland
| | - Alexander A Demkov
- Department of Physics, The University of Texas at Austin, Austin, Texas, 78712, USA.
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36
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Matt CE, Sutter D, Cook AM, Sassa Y, Månsson M, Tjernberg O, Das L, Horio M, Destraz D, Fatuzzo CG, Hauser K, Shi M, Kobayashi M, Strocov VN, Schmitt T, Dudin P, Hoesch M, Pyon S, Takayama T, Takagi H, Lipscombe OJ, Hayden SM, Kurosawa T, Momono N, Oda M, Neupert T, Chang J. Direct observation of orbital hybridisation in a cuprate superconductor. Nat Commun 2018; 9:972. [PMID: 29511188 PMCID: PMC5840306 DOI: 10.1038/s41467-018-03266-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 02/01/2018] [Indexed: 11/19/2022] Open
Abstract
The minimal ingredients to explain the essential physics of layered copper-oxide (cuprates) materials remains heavily debated. Effective low-energy single-band models of the copper–oxygen orbitals are widely used because there exists no strong experimental evidence supporting multi-band structures. Here, we report angle-resolved photoelectron spectroscopy experiments on La-based cuprates that provide direct observation of a two-band structure. This electronic structure, qualitatively consistent with density functional theory, is parametrised by a two-orbital (\documentclass[12pt]{minimal}
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\begin{document}$$d_{z^2}$$\end{document}dz2) tight-binding model. We quantify the orbital hybridisation which provides an explanation for the Fermi surface topology and the proximity of the van-Hove singularity to the Fermi level. Our analysis leads to a unification of electronic hopping parameters for single-layer cuprates and we conclude that hybridisation, restraining d-wave pairing, is an important optimisation element for superconductivity. The essential physics of cuprate superconductors is often described by single-band models. Here, Matt et al. report direct observation of a two-band electronic structure in La-based cuprates.
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Affiliation(s)
- C E Matt
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland. .,Swiss Light Source, Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland.
| | - D Sutter
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - A M Cook
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - Y Sassa
- Department of Physics and Astronomy, Uppsala University, SE-75121, Uppsala, Sweden
| | - M Månsson
- Materials Physics, KTH Royal Institute of Technology, SE-164 40, Kista, Stockholm, Sweden
| | - O Tjernberg
- Materials Physics, KTH Royal Institute of Technology, SE-164 40, Kista, Stockholm, Sweden
| | - L Das
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - M Horio
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - D Destraz
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - C G Fatuzzo
- Institute of Physics, École Polytechnique Fedérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - K Hauser
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - M Kobayashi
- Swiss Light Source, Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - T Schmitt
- Swiss Light Source, Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland
| | - P Dudin
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - S Pyon
- Department of Advanced Materials, University of Tokyo, Kashiwa, 277-8561, Japan
| | - T Takayama
- Department of Advanced Materials, University of Tokyo, Kashiwa, 277-8561, Japan
| | - H Takagi
- Department of Advanced Materials, University of Tokyo, Kashiwa, 277-8561, Japan
| | - O J Lipscombe
- H. H. Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK
| | - S M Hayden
- H. H. Wills Physics Laboratory, University of Bristol, Bristol, BS8 1TL, UK
| | - T Kurosawa
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - N Momono
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan.,Department of Applied Sciences, Muroran Institute of Technology, Muroran, 050-8585, Japan
| | - M Oda
- Department of Physics, Hokkaido University, Sapporo, 060-0810, Japan
| | - T Neupert
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland
| | - J Chang
- Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
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37
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Chen QY, Xu DF, Niu XH, Peng R, Xu HC, Wen CHP, Liu X, Shu L, Tan SY, Lai XC, Zhang YJ, Lee H, Strocov VN, Bisti F, Dudin P, Zhu JX, Yuan HQ, Kirchner S, Feng DL. Band Dependent Interlayer f-Electron Hybridization in CeRhIn_{5}. Phys Rev Lett 2018; 120:066403. [PMID: 29481263 DOI: 10.1103/physrevlett.120.066403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 01/02/2018] [Indexed: 06/08/2023]
Abstract
A key issue in heavy fermion research is how subtle changes in the hybridization between the 4f (5f) and conduction electrons can result in fundamentally different ground states. CeRhIn_{5} stands out as a particularly notable example: when replacing Rh with either Co or Ir, antiferromagnetism gives way to superconductivity. In this photoemission study of CeRhIn_{5}, we demonstrate that the use of resonant angle-resolved photoemission spectroscopy with polarized light allows us to extract detailed information on the 4f crystal field states and details on the 4f and conduction electron hybridization, which together determine the ground state. We directly observe weakly dispersive Kondo resonances of f electrons and identify two of the three Ce 4f_{5/2}^{1} crystal-electric-field levels and band-dependent hybridization, which signals that the hybridization occurs primarily between the Ce 4f states in the CeIn_{3} layer and two more three-dimensional bands composed of the Rh 4d and In 5p orbitals in the RhIn_{2} layer. Our results allow us to connect the properties observed at elevated temperatures with the unusual low-temperature properties of this enigmatic heavy fermion compound.
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Affiliation(s)
- Q Y Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China
| | - D F Xu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - X H Niu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - R Peng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - H C Xu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - C H P Wen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - X Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - L Shu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - S Y Tan
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China
| | - X C Lai
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621908, China
| | - Y J Zhang
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - H Lee
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - P Dudin
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - J-X Zhu
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - H Q Yuan
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
- Department of Physics, Zhejiang University, Hangzhou 310027, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - S Kirchner
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, China
| | - D L Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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38
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Schütz P, Di Sante D, Dudy L, Gabel J, Stübinger M, Kamp M, Huang Y, Capone M, Husanu MA, Strocov VN, Sangiovanni G, Sing M, Claessen R. Dimensionality-Driven Metal-Insulator Transition in Spin-Orbit-Coupled SrIrO_{3}. Phys Rev Lett 2017; 119:256404. [PMID: 29303315 DOI: 10.1103/physrevlett.119.256404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Indexed: 05/27/2023]
Abstract
Upon reduction of the film thickness we observe a metal-insulator transition in epitaxially stabilized, spin-orbit-coupled SrIrO_{3} ultrathin films. By comparison of the experimental electronic dispersions with density functional theory at various levels of complexity we identify the leading microscopic mechanisms, i.e., a dimensionality-induced readjustment of octahedral rotations, magnetism, and electronic correlations. The astonishing resemblance of the band structure in the two-dimensional limit to that of bulk Sr_{2}IrO_{4} opens new avenues to unconventional superconductivity by "clean" electron doping through electric field gating.
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Affiliation(s)
- P Schütz
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - D Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - L Dudy
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - J Gabel
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Stübinger
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Kamp
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Y Huang
- Van der Waals-Zeeman Insitute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - M Capone
- CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
| | - M-A Husanu
- National Institute of Materials Physics, Atomistilor 405 A, 077125 Magurele, Romania
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - G Sangiovanni
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Sing
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - R Claessen
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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39
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Di Sante D, Das PK, Bigi C, Ergönenc Z, Gürtler N, Krieger JA, Schmitt T, Ali MN, Rossi G, Thomale R, Franchini C, Picozzi S, Fujii J, Strocov VN, Sangiovanni G, Vobornik I, Cava RJ, Panaccione G. Three-Dimensional Electronic Structure of the Type-II Weyl Semimetal WTe_{2}. Phys Rev Lett 2017; 119:026403. [PMID: 28753342 DOI: 10.1103/physrevlett.119.026403] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Indexed: 06/07/2023]
Abstract
By combining bulk sensitive soft-x-ray angular-resolved photoemission spectroscopy and first-principles calculations we explored the bulk electron states of WTe_{2}, a candidate type-II Weyl semimetal featuring a large nonsaturating magnetoresistance. Despite the layered geometry suggesting a two-dimensional electronic structure, we directly observe a three-dimensional electronic dispersion. We report a band dispersion in the reciprocal direction perpendicular to the layers, implying that electrons can also travel coherently when crossing from one layer to the other. The measured Fermi surface is characterized by two well-separated electron and hole pockets at either side of the Γ point, differently from previous more surface sensitive angle-resolved photoemission spectroscopy experiments that additionally found a pronounced quasiparticle weight at the zone center. Moreover, we observe a significant sensitivity of the bulk electronic structure of WTe_{2} around the Fermi level to electronic correlations and renormalizations due to self-energy effects, previously neglected in first-principles descriptions.
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Affiliation(s)
- Domenico Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
| | - Pranab Kumar Das
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
- International Centre for Theoretical Physics (ICTP), Strada Costiera 11, I-34100 Trieste, Italy
| | - C Bigi
- Dipartimento di Fisica, Universitá di Milano, Via Celoria 16, I-20133 Milano, Italy
| | - Z Ergönenc
- Computational Materials Physics, University of Vienna, Sensengasse 8/8, A-1090 Vienna, Austria
| | - N Gürtler
- Computational Materials Physics, University of Vienna, Sensengasse 8/8, A-1090 Vienna, Austria
| | - J A Krieger
- Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
- Laboratorium für Festkörperphysik, ETH-Hönggerberg, CH-8093 Zürich, Switzerland
| | - T Schmitt
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen, Switzerland
| | - M N Ali
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - G Rossi
- Dipartimento di Fisica, Universitá di Milano, Via Celoria 16, I-20133 Milano, Italy
| | - R Thomale
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
| | - C Franchini
- Computational Materials Physics, University of Vienna, Sensengasse 8/8, A-1090 Vienna, Austria
| | - S Picozzi
- Consiglio Nazionale delle Ricerche (CNR-SPIN), Via Vetoio, L'Aquila 67100, Italy
| | - J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - V N Strocov
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen, Switzerland
| | - G Sangiovanni
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland Campus Süd, Würzburg 97074, Germany
| | - I Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
| | - R J Cava
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA
| | - G Panaccione
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, in Area Science Park, S.S.14, Km 163.5, I-34149 Trieste, Italy
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40
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Xu SY, Alidoust N, Chang G, Lu H, Singh B, Belopolski I, Sanchez DS, Zhang X, Bian G, Zheng H, Husanu MA, Bian Y, Huang SM, Hsu CH, Chang TR, Jeng HT, Bansil A, Neupert T, Strocov VN, Lin H, Jia S, Hasan MZ. Discovery of Lorentz-violating type II Weyl fermions in LaAlGe. Sci Adv 2017; 3:e1603266. [PMID: 28630919 PMCID: PMC5457030 DOI: 10.1126/sciadv.1603266] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/07/2017] [Indexed: 05/17/2023]
Abstract
In quantum field theory, Weyl fermions are relativistic particles that travel at the speed of light and strictly obey the celebrated Lorentz symmetry. Their low-energy condensed matter analogs are Weyl semimetals, which are conductors whose electronic excitations mimic the Weyl fermion equation of motion. Although the traditional (type I) emergent Weyl fermions observed in TaAs still approximately respect Lorentz symmetry, recently, the so-called type II Weyl semimetal has been proposed, where the emergent Weyl quasiparticles break the Lorentz symmetry so strongly that they cannot be smoothly connected to Lorentz symmetric Weyl particles. Despite some evidence of nontrivial surface states, the direct observation of the type II bulk Weyl fermions remains elusive. We present the direct observation of the type II Weyl fermions in crystalline solid lanthanum aluminum germanide (LaAlGe) based on our photoemission data alone, without reliance on band structure calculations. Moreover, our systematic data agree with the theoretical calculations, providing further support on our experimental results.
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Affiliation(s)
- Su-Yang Xu
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
| | - Nasser Alidoust
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
- Rigetti & Co Inc., 775 Heinz Avenue, Berkeley, CA 94710, USA
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Hong Lu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Bahadur Singh
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Ilya Belopolski
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
| | - Daniel S. Sanchez
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
| | - Xiao Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Guang Bian
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
- Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA
| | - Hao Zheng
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
| | - Marious-Adrian Husanu
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
- National Institute of Materials Physics, 405A Atomistilor Street, 077125 Magurele, Romania
| | - Yi Bian
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
- Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Chuang-Han Hsu
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Titus Neupert
- Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8052, Switzerland
| | - Vladimir N. Strocov
- Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen PSI, Switzerland
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - M. Zahid Hasan
- Department of Physics, Laboratory for Topological Quantum Matter and Spectroscopy (B7), Princeton University, Princeton, NJ 08544, USA
- Corresponding author.
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41
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Schreck S, Pietzsch A, Kennedy B, Såthe C, Miedema PS, Techert S, Strocov VN, Schmitt T, Hennies F, Rubensson JE, Föhlisch A. Erratum: Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering. Sci Rep 2017; 7:46386. [PMID: 28664929 PMCID: PMC5492273 DOI: 10.1038/srep46386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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42
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Xu N, Autès G, Matt CE, Lv BQ, Yao MY, Bisti F, Strocov VN, Gawryluk D, Pomjakushina E, Conder K, Plumb NC, Radovic M, Qian T, Yazyev OV, Mesot J, Ding H, Shi M. Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals. Phys Rev Lett 2017; 118:106406. [PMID: 28339253 DOI: 10.1103/physrevlett.118.106406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Indexed: 06/06/2023]
Abstract
The Weyl semimetal phase is a recently discovered topological quantum state of matter characterized by the presence of topologically protected degeneracies near the Fermi level. These degeneracies are the source of exotic phenomena, including the realization of chiral Weyl fermions as quasiparticles in the bulk and the formation of Fermi arc states on the surfaces. Here, we demonstrate that these two key signatures show distinct evolutions with the bulk band topology by performing angle-resolved photoemission spectroscopy, supported by first-principles calculations, on transition-metal monophosphides. While Weyl fermion quasiparticles exist only when the chemical potential is located between two saddle points of the Weyl cone features, the Fermi arc states extend in a larger energy scale and are robust across the bulk Lifshitz transitions associated with the recombination of two nontrivial Fermi surfaces enclosing one Weyl point into a single trivial Fermi surface enclosing two Weyl points of opposite chirality. Therefore, in some systems (e.g., NbP), topological Fermi arc states are preserved even if Weyl fermion quasiparticles are absent in the bulk. Our findings not only provide insight into the relationship between the exotic physical phenomena and the intrinsic bulk band topology in Weyl semimetals, but also resolve the apparent puzzle of the different magnetotransport properties observed in TaAs, TaP, and NbP, where the Fermi arc states are similar.
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Affiliation(s)
- N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - G Autès
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - B Q Lv
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - M Y Yao
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - D Gawryluk
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - O V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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43
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Belopolski I, Xu SY, Koirala N, Liu C, Bian G, Strocov VN, Chang G, Neupane M, Alidoust N, Sanchez D, Zheng H, Brahlek M, Rogalev V, Kim T, Plumb NC, Chen C, Bertran F, Le Fèvre P, Taleb-Ibrahimi A, Asensio MC, Shi M, Lin H, Hoesch M, Oh S, Hasan MZ. A novel artificial condensed matter lattice and a new platform for one-dimensional topological phases. Sci Adv 2017; 3:e1501692. [PMID: 28378013 PMCID: PMC5365246 DOI: 10.1126/sciadv.1501692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/28/2017] [Indexed: 06/07/2023]
Abstract
Engineered lattices in condensed matter physics, such as cold-atom optical lattices or photonic crystals, can have properties that are fundamentally different from those of naturally occurring electronic crystals. We report a novel type of artificial quantum matter lattice. Our lattice is a multilayer heterostructure built from alternating thin films of topological and trivial insulators. Each interface within the heterostructure hosts a set of topologically protected interface states, and by making the layers sufficiently thin, we demonstrate for the first time a hybridization of interface states across layers. In this way, our heterostructure forms an emergent atomic chain, where the interfaces act as lattice sites and the interface states act as atomic orbitals, as seen from our measurements by angle-resolved photoemission spectroscopy. By changing the composition of the heterostructure, we can directly control hopping between lattice sites. We realize a topological and a trivial phase in our superlattice band structure. We argue that the superlattice may be characterized in a significant way by a one-dimensional topological invariant, closely related to the invariant of the Su-Schrieffer-Heeger model. Our topological insulator heterostructure demonstrates a novel experimental platform where we can engineer band structures by directly controlling how electrons hop between lattice sites.
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Affiliation(s)
- Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Nikesh Koirala
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 USA
| | - Chang Liu
- Department of Physics, South University of Science and Technology of China, Shenzhen, Guangdong 518055, China
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Vladimir N. Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Guoqing Chang
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Madhab Neupane
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Daniel Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Matthew Brahlek
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 USA
| | - Victor Rogalev
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Physikalisches Institut and Röntgen Center for Complex Material Systems, Universität Würzburg, 97074 Würzburg, Germany
| | - Timur Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - Nicholas C. Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Chaoyu Chen
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - François Bertran
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Patrick Le Fèvre
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Amina Taleb-Ibrahimi
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Maria-Carmen Asensio
- Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Ming Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Hsin Lin
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Moritz Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - Seongshik Oh
- Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 USA
| | - M. Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
- Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
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44
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Razzoli E, Jaouen T, Mottas ML, Hildebrand B, Monney G, Pisoni A, Muff S, Fanciulli M, Plumb NC, Rogalev VA, Strocov VN, Mesot J, Shi M, Dil JH, Beck H, Aebi P. Selective Probing of Hidden Spin-Polarized States in Inversion-Symmetric Bulk MoS_{2}. Phys Rev Lett 2017; 118:086402. [PMID: 28282191 DOI: 10.1103/physrevlett.118.086402] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Indexed: 06/06/2023]
Abstract
Spin- and angle-resolved photoemission spectroscopy is used to reveal that a large spin polarization is observable in the bulk centrosymmetric transition metal dichalcogenide MoS_{2}. It is found that the measured spin polarization can be reversed by changing the handedness of incident circularly polarized light. Calculations based on a three-step model of photoemission show that the valley and layer-locked spin-polarized electronic states can be selectively addressed by circularly polarized light, therefore providing a novel route to probe these hidden spin-polarized states in inversion-symmetric systems as predicted by Zhang et al. [Nat. Phys. 10, 387 (2014).NPAHAX1745-247310.1038/nphys2933].
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Affiliation(s)
- E Razzoli
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
| | - T Jaouen
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
| | - M-L Mottas
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
| | - B Hildebrand
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
| | - G Monney
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
| | - A Pisoni
- Laboratory of Physics of Complex Matter, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - S Muff
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - M Fanciulli
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - V A Rogalev
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - J H Dil
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - H Beck
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
| | - P Aebi
- Département de Physique and Fribourg Center for Nanomaterials, Université de Fribourg, CH-1700 Fribourg, Switzerland
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45
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Manzoni G, Gragnaniello L, Autès G, Kuhn T, Sterzi A, Cilento F, Zacchigna M, Enenkel V, Vobornik I, Barba L, Bisti F, Bugnon P, Magrez A, Strocov VN, Berger H, Yazyev OV, Fonin M, Parmigiani F, Crepaldi A. Evidence for a Strong Topological Insulator Phase in ZrTe_{5}. Phys Rev Lett 2016; 117:237601. [PMID: 27982645 DOI: 10.1103/physrevlett.117.237601] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Indexed: 05/05/2023]
Abstract
The complex electronic properties of ZrTe_{5} have recently stimulated in-depth investigations that assigned this material to either a topological insulator or a 3D Dirac semimetal phase. Here we report a comprehensive experimental and theoretical study of both electronic and structural properties of ZrTe_{5}, revealing that the bulk material is a strong topological insulator (STI). By means of angle-resolved photoelectron spectroscopy, we identify at the top of the valence band both a surface and a bulk state. The dispersion of these bands is well captured by ab initio calculations for the STI case, for the specific interlayer distance measured in our x-ray diffraction study. Furthermore, these findings are supported by scanning tunneling spectroscopy revealing the metallic character of the sample surface, thus confirming the strong topological nature of ZrTe_{5}.
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Affiliation(s)
- G Manzoni
- Universitá degli Studi di Trieste, Via Alfonso Valerio 2, Trieste 34127, Italy
| | - L Gragnaniello
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - G Autès
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - T Kuhn
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - A Sterzi
- Universitá degli Studi di Trieste, Via Alfonso Valerio 2, Trieste 34127, Italy
| | - F Cilento
- Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, Trieste I-34149, Italy
| | - M Zacchigna
- Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park - Basovizza, I-34149 Trieste, Italy
| | - V Enenkel
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - I Vobornik
- Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park - Basovizza, I-34149 Trieste, Italy
| | - L Barba
- Institute of Crystallography, CNR, Area Science Park, Strada Statale 14, km 163.5 Trieste I-34149, Italy
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Ph Bugnon
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - A Magrez
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - H Berger
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - O V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - M Fonin
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - F Parmigiani
- Universitá degli Studi di Trieste, Via Alfonso Valerio 2, Trieste 34127, Italy
- Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, Trieste I-34149, Italy
- International Faculty, University of Köln, 50937 Köln, Germany
| | - A Crepaldi
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Elettra-Sincrotrone Trieste S.C.p.A., Strada Statale 14, km 163.5, Trieste I-34149, Italy
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46
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Bouravleuv AD, Lev LL, Piamonteze C, Wang X, Schmitt T, Khrebtov AI, Samsonenko YB, Kanski J, Cirlin GE, Strocov VN. Electronic structure of (In,Mn)As quantum dots buried in GaAs investigated by soft-x-ray ARPES. Nanotechnology 2016; 27:425706. [PMID: 27631689 DOI: 10.1088/0957-4484/27/42/425706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Electronic structure of a molecular beam epitaxy-grown system of (In,Mn)As quantum dots (QDs) buried in GaAs is explored with soft-x-ray angle-resolved photoelectron spectroscopy (ARPES) using photon energies around 1 keV. This technique, ideally suited for buried systems, extends the momentum-resolving capabilities of conventional ARPES with enhanced probing depth as well as elemental and chemical state specificity achieved with resonant photoexcitation. The experimental results resolve the dispersive energy bands of the GaAs substrate buried in ∼2 nm below the surface, and the impurity states (ISs) derived from the substitutional Mn atoms in the (In,Mn)As QDs and oxidized Mn atoms distributed near the surface. An energy shift of the Mn ISs in the QDs compared to (In,Mn)As DMS is attributed to the band offset and proximity effect at the interface with the surrounding GaAs. The absence of any ISs in the vicinity of the VBM relates the electron transport in (In,Mn)As QDs to the prototype (In,Mn)As diluted magnetic semiconductor. The SX-ARPES results are supported by measurements of the shallow core levels under variation of probing depth through photon energy. X-ray absorption measurements identify significant diffusion of interstitial Mn atoms out of the QDs towards the surface, and the role of magnetic circular dichroism is to block the ferromagnetic response of the (In,Mn)As QDs. Possible routes are drawn to tune the growth procedure aiming at practical applications of the (In,Mn)As based systems.
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Affiliation(s)
- A D Bouravleuv
- St.Petersburg Academic University RAS, 8-3 Khlopina st., 194021 St.Petersburg, Russia. Ioffe Physical Technical Institute RAS, 26 Politekhnicheskaya st., 194021 St.Petersburg, Russia. Institute for Analytical Instrumentation RAS, 31-33 Ivana Chernykh st., 190103 St.Petersburg, Russia. St.Petersburg State University, 7-9 Universitetskaya nab., 199034 St.Petersburg, Russia
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47
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Krempaský J, Muff S, Bisti F, Fanciulli M, Volfová H, Weber AP, Pilet N, Warnicke P, Ebert H, Braun J, Bertran F, Volobuev VV, Minár J, Springholz G, Dil JH, Strocov VN. Entanglement and manipulation of the magnetic and spin-orbit order in multiferroic Rashba semiconductors. Nat Commun 2016; 7:13071. [PMID: 27767052 PMCID: PMC5078730 DOI: 10.1038/ncomms13071] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/31/2016] [Indexed: 11/17/2022] Open
Abstract
Entanglement of the spin–orbit and magnetic order in multiferroic materials bears a strong potential for engineering novel electronic and spintronic devices. Here, we explore the electron and spin structure of ferroelectric α-GeTe thin films doped with ferromagnetic Mn impurities to achieve its multiferroic functionality. We use bulk-sensitive soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to follow hybridization of the GeTe valence band with the Mn dopants. We observe a gradual opening of the Zeeman gap in the bulk Rashba bands around the Dirac point with increase of the Mn concentration, indicative of the ferromagnetic order, at persistent Rashba splitting. Furthermore, subtle details regarding the spin–orbit and magnetic order entanglement are deduced from spin-resolved ARPES measurements. We identify antiparallel orientation of the ferroelectric and ferromagnetic polarization, and altering of the Rashba-type spin helicity by magnetic switching. Our experimental results are supported by first-principles calculations of the electron and spin structure. In α-GeTe, ferroelectric polarization acts to break inversion symmetry of the lattice and induce a strong Rashba-type spin splitting of the electronic band structure. Here, the authors study how this effect competes with Zeeman splitting due to ferromagnetic exchange coupling in Mn-doped GeTe.
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Affiliation(s)
- J Krempaský
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - S Muff
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Fanciulli
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - H Volfová
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany
| | - A P Weber
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - N Pilet
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - P Warnicke
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - H Ebert
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany
| | - J Braun
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany
| | - F Bertran
- SOLEIL Synchrotron, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France
| | - V V Volobuev
- National Technical University, Kharkiv Polytechnic Institute, Frunze Str. 21, 61002 Kharkiv, Ukraine.,Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - J Minár
- Department of Chemistry, Ludwig Maximillian University, 81377 Munich, Germany.,New Technologies-Research Center University of West Bohemia, Plzeň, Czech Republic
| | - G Springholz
- Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
| | - J H Dil
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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48
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Bisogni V, Catalano S, Green RJ, Gibert M, Scherwitzl R, Huang Y, Strocov VN, Zubko P, Balandeh S, Triscone JM, Sawatzky G, Schmitt T. Ground-state oxygen holes and the metal-insulator transition in the negative charge-transfer rare-earth nickelates. Nat Commun 2016; 7:13017. [PMID: 27725665 PMCID: PMC5062575 DOI: 10.1038/ncomms13017] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 08/25/2016] [Indexed: 11/13/2022] Open
Abstract
The metal–insulator transition and the intriguing physical properties of rare-earth perovskite nickelates have attracted considerable attention in recent years. Nonetheless, a complete understanding of these materials remains elusive. Here we combine X-ray absorption and resonant inelastic X-ray scattering (RIXS) spectroscopies to resolve important aspects of the complex electronic structure of rare-earth nickelates, taking NdNiO3 thin film as representative example. The unusual coexistence of bound and continuum excitations observed in the RIXS spectra provides strong evidence for abundant oxygen holes in the ground state of these materials. Using cluster calculations and Anderson impurity model interpretation, we show that distinct spectral signatures arise from a Ni 3d8 configuration along with holes in the oxygen 2p valence band, confirming suggestions that these materials do not obey a conventional positive charge-transfer picture, but instead exhibit a negative charge-transfer energy in line with recent models interpreting the metal–insulator transition in terms of bond disproportionation. Rare-earth perovskite nickelates show intriguing metal–insulator transitions, whose mechanism remains elusive. Here, Bisogni et al. evidenced a 3d8 Ni configuration together with abundance of oxygen 2p holes in the ground state of a NdNiO3 thin film, suggesting a negative charge-transfer scenario.
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Affiliation(s)
- Valentina Bisogni
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Sara Catalano
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Robert J Green
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.,Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Marta Gibert
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Raoul Scherwitzl
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Yaobo Huang
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.,Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Vladimir N Strocov
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Pavlo Zubko
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland.,London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, 17-19 Gordon Street, London WC1H 0HA, UK
| | - Shadi Balandeh
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1
| | - Jean-Marc Triscone
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - George Sawatzky
- Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1.,Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Thorsten Schmitt
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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49
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Johnston S, Monney C, Bisogni V, Zhou KJ, Kraus R, Behr G, Strocov VN, Málek J, Drechsler SL, Geck J, Schmitt T, van den Brink J. Electron-lattice interactions strongly renormalize the charge-transfer energy in the spin-chain cuprate Li2CuO2. Nat Commun 2016; 7:10563. [PMID: 26884151 PMCID: PMC4757783 DOI: 10.1038/ncomms10563] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/26/2015] [Indexed: 11/09/2022] Open
Abstract
Strongly correlated insulators are broadly divided into two classes: Mott-Hubbard insulators, where the insulating gap is driven by the Coulomb repulsion U on the transition-metal cation, and charge-transfer insulators, where the gap is driven by the charge-transfer energy Δ between the cation and the ligand anions. The relative magnitudes of U and Δ determine which class a material belongs to, and subsequently the nature of its low-energy excitations. These energy scales are typically understood through the local chemistry of the active ions. Here we show that the situation is more complex in the low-dimensional charge-transfer insulator Li2CuO2, where Δ has a large non-electronic component. Combining resonant inelastic X-ray scattering with detailed modelling, we determine how the elementary lattice, charge, spin and orbital excitations are entangled in this material. This results in a large lattice-driven renormalization of Δ, which significantly reshapes the fundamental electronic properties of Li2CuO2.
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Affiliation(s)
- Steve Johnston
- Department of Physics and Astronomy, The University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Claude Monney
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland.,Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Valentina Bisogni
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany.,National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Ke-Jin Zhou
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland.,Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Roberto Kraus
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Günter Behr
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Vladimir N Strocov
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland
| | - Jiři Málek
- Institute of Physics, ASCR, Na Slovance 2, CZ-18221 Praha 8, Czech Republic
| | - Stefan-Ludwig Drechsler
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Jochen Geck
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany
| | - Thorsten Schmitt
- Research Department Synchrotron Radiation and Nanotechnology, Paul Scherrer Institut, CH-5232, Villigen, Switzerland
| | - Jeroen van den Brink
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, D-01171 Dresden, Germany.,Department of Physics, TU Dresden, D-01062 Dresden, Germany
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50
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Schreck S, Pietzsch A, Kennedy B, Såthe C, Miedema PS, Techert S, Strocov VN, Schmitt T, Hennies F, Rubensson JE, Föhlisch A. Ground state potential energy surfaces around selected atoms from resonant inelastic x-ray scattering. Sci Rep 2016; 7:20054. [PMID: 26821751 PMCID: PMC4731820 DOI: 10.1038/srep20054] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 11/27/2015] [Indexed: 11/24/2022] Open
Abstract
Thermally driven chemistry as well as materials’ functionality are determined by the potential energy surface of a systems electronic ground state. This makes the potential energy surface a central and powerful concept in physics, chemistry and materials science. However, direct experimental access to the potential energy surface locally around atomic centers and to its long-range structure are lacking. Here we demonstrate how sub-natural linewidth resonant inelastic soft x-ray scattering at vibrational resolution is utilized to determine ground state potential energy surfaces locally and detect long-range changes of the potentials that are driven by local modifications. We show how the general concept is applicable not only to small isolated molecules such as O2 but also to strongly interacting systems such as the hydrogen bond network in liquid water. The weak perturbation to the potential energy surface through hydrogen bonding is observed as a trend towards softening of the ground state potential around the coordinating atom. The instrumental developments in high resolution resonant inelastic soft x-ray scattering are currently accelerating and will enable broad application of the presented approach. With this multidimensional potential energy surfaces that characterize collective phenomena such as (bio)molecular function or high-temperature superconductivity will become accessible in near future.
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Affiliation(s)
- Simon Schreck
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.,Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
| | - Annette Pietzsch
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Brian Kennedy
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Conny Såthe
- Max IV Laboratory, Box 118, 22100 Lund, Sweden
| | - Piter S Miedema
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - Simone Techert
- FS-Structural Dynamics in (Bio)chemistry, Deutsches Elektronen-Synchrotron, Notkestrasse 85, 22607 Hamburg, Germany.,Max Planck Institute for Biophysical Chemistry, Am Faß berg 11, 37077 Göttingen, Germany.,Institute for X-ray Physics, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Vladimir N Strocov
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | - Thorsten Schmitt
- Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland
| | | | - Jan-Erik Rubensson
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Alexander Föhlisch
- Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany.,Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany
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