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Hahn S, Sohn B, Kim M, Kim JR, Huh S, Kim Y, Kyung W, Kim M, Kim D, Kim Y, Noh TW, Shim JH, Kim C. Observation of Spin-Dependent Dual Ferromagnetism in Perovskite Ruthenates. PHYSICAL REVIEW LETTERS 2021; 127:256401. [PMID: 35029413 DOI: 10.1103/physrevlett.127.256401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 11/11/2021] [Indexed: 06/14/2023]
Abstract
We performed in situ angle-resolved photoemission spectroscopy (ARPES) and spin-resolved ARPES (SARPES) experiments to investigate the relationship between electronic band structures and ferromagnetism in SrRuO_{3} (SRO) thin films. Our high quality ARPES and SARPES results show clear spin-lifted band structures. The spin polarization is strongly dependent on momentum around the Fermi level, whereas it becomes less dependent at high-binding energies. This experimental observation matches our dynamical mean-field theory results very well. As temperature increases from low to the Curie temperature, spin-splitting gap decreases and band dispersions become incoherent. Based on the ARPES study and theoretical calculation results, we found that SRO possesses spin-dependent electron correlations in which majority and minority spins are localized and itinerant, respectively. Our finding explains how ferromagnetism and electronic structure are connected, which has been under debate for decades in SRO.
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Affiliation(s)
- Sungsoo Hahn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Byungmin Sohn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Minjae Kim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Soonsang Huh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Younsik Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Wonshik Kyung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Minsoo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Youngdo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
| | - Ji Hoon Shim
- Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul 08826, Korea
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2
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King PDC, Picozzi S, Egdell RG, Panaccione G. Angle, Spin, and Depth Resolved Photoelectron Spectroscopy on Quantum Materials. Chem Rev 2021; 121:2816-2856. [PMID: 33346644 DOI: 10.1021/acs.chemrev.0c00616] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The role of X-ray based electron spectroscopies in determining chemical, electronic, and magnetic properties of solids has been well-known for several decades. A powerful approach is angle-resolved photoelectron spectroscopy, whereby the kinetic energy and angle of photoelectrons emitted from a sample surface are measured. This provides a direct measurement of the electronic band structure of crystalline solids. Moreover, it yields powerful insights into the electronic interactions at play within a material and into the control of spin, charge, and orbital degrees of freedom, central pillars of future solid state science. With strong recent focus on research of lower-dimensional materials and modified electronic behavior at surfaces and interfaces, angle-resolved photoelectron spectroscopy has become a core technique in the study of quantum materials. In this review, we provide an introduction to the technique. Through examples from several topical materials systems, including topological insulators, transition metal dichalcogenides, and transition metal oxides, we highlight the types of information which can be obtained. We show how the combination of angle, spin, time, and depth-resolved experiments are able to reveal "hidden" spectral features, connected to semiconducting, metallic and magnetic properties of solids, as well as underlining the importance of dimensional effects in quantum materials.
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Affiliation(s)
- Phil D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Silvia Picozzi
- Consiglio Nazionale delle Ricerche, CNR-SPIN, Via dei Vestini 31, Chieti 66100, Italy
| | - Russell G Egdell
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Giancarlo 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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3
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Signatures of Mottness and Hundness in archetypal correlated metals. Nat Commun 2019; 10:2721. [PMID: 31221960 PMCID: PMC6586627 DOI: 10.1038/s41467-019-10257-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 04/26/2019] [Indexed: 02/06/2023] Open
Abstract
Physical properties of multi-orbital materials depend not only on the strength of the effective interactions among the valence electrons but also on their type. Strong correlations are caused by either Mott physics that captures the Coulomb repulsion among charges, or Hund physics that aligns the spins in different orbitals. We identify four energy scales marking the onset and the completion of screening in orbital and spin channels. The differences in these scales, which are manifest in the temperature dependence of the local spectrum and of the charge, spin and orbital susceptibilities, provide clear signatures distinguishing Mott and Hund physics. We illustrate these concepts with realistic studies of two archetypal strongly correlated materials, and corroborate the generality of our conclusions with a model Hamiltonian study.
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4
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Kink far below the Fermi level reveals new electron-magnon scattering channel in Fe. Nat Commun 2019; 10:505. [PMID: 30705281 PMCID: PMC6355843 DOI: 10.1038/s41467-019-08445-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 01/04/2019] [Indexed: 11/25/2022] Open
Abstract
Many properties of real materials can be modeled using ab initio methods within a single-particle picture. However, for an accurate theoretical treatment of excited states, it is necessary to describe electron-electron correlations including interactions with bosons: phonons, plasmons, or magnons. In this work, by comparing spin- and momentum-resolved photoemission spectroscopy measurements to many-body calculations carried out with a newly developed first-principles method, we show that a kink in the electronic band dispersion of a ferromagnetic material can occur at much deeper binding energies than expected (Eb = 1.5 eV). We demonstrate that the observed spectral signature reflects the formation of a many-body state that includes a photohole bound to a coherent superposition of renormalized spin-flip excitations. The existence of such a many-body state sheds new light on the physics of the electron-magnon interaction which is essential in fields such as spintronics and Fe-based superconductivity. The conduction electron and magnon interactions are essential for the understanding and development of spintronics and superconductivity. Here the authors show a deep binding energy kink in spin-resolved photoemission spectra which is understood as a signature the many-body spin flip excitation in Fe single crystal thin film.
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5
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Tusche C, Ellguth M, Feyer V, Krasyuk A, Wiemann C, Henk J, Schneider CM, Kirschner J. Nonlocal electron correlations in an itinerant ferromagnet. Nat Commun 2018; 9:3727. [PMID: 30213929 PMCID: PMC6137183 DOI: 10.1038/s41467-018-05960-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 07/27/2018] [Indexed: 11/29/2022] Open
Abstract
Our understanding of the properties of ferromagnetic materials, widely used in spintronic devices, is fundamentally based on their electronic band structure. However, even for the most simple elemental ferromagnets, electron correlations are prevalent, requiring descriptions of their electronic structure beyond the simple picture of independent quasi-particles. Here, we give evidence that in itinerant ferromagnets like cobalt these electron correlations are of nonlocal origin, manifested in a complex self-energy Σσ(E,k) that disperses as function of spin σ, energy E, and momentum vector k. Together with one-step photoemission calculations, our experiments allow us to quantify the dispersive behaviour of the complex self-energy over the whole Brillouin zone. At the same time we observe regions of anomalously large "waterfall"-like band renormalization, previously only attributed to strong electron correlations in high-TC superconductors, making itinerant ferromagnets a paradigmatic test case for the interplay between band structure, magnetism, and many-body correlations.
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Affiliation(s)
- Christian Tusche
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany.
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany.
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany.
| | - Martin Ellguth
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Vitaliy Feyer
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Alexander Krasyuk
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
| | - Carsten Wiemann
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
| | - Jürgen Henk
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle, Germany
| | - Claus M Schneider
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-6), 52425, Jülich, Germany
- Fakultät für Physik, Universität Duisburg-Essen, 47057, Duisburg, Germany
| | - Jürgen Kirschner
- Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120, Halle, Germany
- Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06120, Halle, Germany
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Abstract
Relativistic massless Dirac fermions can be probed with high-energy physics experiments, but appear also as low-energy quasi-particle excitations in electronic band structures. In condensed matter systems, their massless nature can be protected by crystal symmetries. Classification of such symmetry-protected relativistic band degeneracies has been fruitful, although many of the predicted quasi-particles still await their experimental discovery. Here we reveal, using angle-resolved photoemission spectroscopy, the existence of two-dimensional type-II Dirac fermions in the high-temperature superconductor La1.77Sr0.23CuO4. The Dirac point, constituting the crossing of \documentclass[12pt]{minimal}
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\begin{document}$$d_{z^2}$$\end{document}dz2 bands, is found approximately one electronvolt below the Fermi level (EF) and is protected by mirror symmetry. If spin-orbit coupling is considered, the Dirac point degeneracy is lifted and the bands acquire a topologically non-trivial character. In certain nickelate systems, band structure calculations suggest that the same type-II Dirac fermions can be realised near EF. Many predicted topological quasi-particles still await experimental discovery. Here, Horio et al. reveal the existence of two-dimensional type-II Dirac fermions in the high-temperature superconductor La1.77Sr0.23CuO4, promoting layered oxides as promising topological materials.
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Kim M, Mravlje J, Ferrero M, Parcollet O, Georges A. Spin-Orbit Coupling and Electronic Correlations in Sr_{2}RuO_{4}. PHYSICAL REVIEW LETTERS 2018; 120:126401. [PMID: 29694056 DOI: 10.1103/physrevlett.120.126401] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 02/20/2018] [Indexed: 06/08/2023]
Abstract
We investigate the interplay of spin-orbit coupling (SOC) and electronic correlations in Sr_{2}RuO_{4} using dynamical mean-field theory. We find that SOC does not affect the correlation-induced renormalizations, which validates Hund's metal picture of ruthenates even in the presence of the sizable SOC relevant to these materials. Nonetheless, SOC is found to change significantly the electronic structure at k points where a degeneracy applies in its absence. We explain why these two observations are consistent with one another and calculate the effects of SOC on the correlated electronic structure. The magnitude of these effects is found to depend on the energy of the quasiparticle state under consideration, leading us to introduce the notion of an energy-dependent quasiparticle spin-orbit coupling λ^{*}(ω). This notion is generally applicable to all materials in which both the spin-orbit coupling and electronic correlations are sizable.
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Affiliation(s)
- Minjae Kim
- Centre de Physique Théorique, École Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
- Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
| | - Jernej Mravlje
- Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia
| | - Michel Ferrero
- Centre de Physique Théorique, École Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
- Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
| | - Olivier Parcollet
- Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
- Institut de Physique Théorique (IPhT), CEA, CNRS, 91191 Gif-sur-Yvette, France
| | - Antoine Georges
- Centre de Physique Théorique, École Polytechnique, CNRS, Université Paris-Saclay, 91128 Palaiseau, France
- Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
- Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth avenue, New York, New York 10010, USA
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
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8
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Zhang Y, Lu H, Zhu X, Tan S, Feng W, Liu Q, Zhang W, Chen Q, Liu Y, Luo X, Xie D, Luo L, Zhang Z, Lai X. Emergence of Kondo lattice behavior in a van der Waals itinerant ferromagnet, Fe 3GeTe 2. SCIENCE ADVANCES 2018; 4:eaao6791. [PMID: 29349301 PMCID: PMC5770166 DOI: 10.1126/sciadv.aao6791] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/29/2017] [Indexed: 05/28/2023]
Abstract
Searching for heavy fermion (HF) states in non-f-electron systems becomes an interesting issue, especially in the presence of magnetism, and can help explain the physics of complex compounds. Using angle-resolved photoemission spectroscopy, scanning tunneling microscopy, physical properties measurements, and the first-principles calculations, we observe the HF state in a 3d-electron van der Waals ferromagnet, Fe3GeTe2. Upon entering the ferromagnetic state, a massive spectral weight transfer occurs, which results from the exchange splitting. Meanwhile, the Fermi surface volume and effective electron mass are both enhanced. When the temperature drops below a characteristic temperature T*, heavy electrons gradually emerge with further enhanced effective electron mass. The coexistence of ferromagnetism and HF state can be well interpreted by the dual properties (itinerant and localized) of 3d electrons. This work expands the limit of ferromagnetic HF materials from f- to d-electron systems and illustrates the positive correlation between ferromagnetism and HF state in the 3d-electron material, which is quite different from the f-electron systems.
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Affiliation(s)
- Yun Zhang
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
- Department of Engineering Physics, Tsinghua University, Beijing 100084, China
| | - Haiyan Lu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Xiegang Zhu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Shiyong Tan
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Wei Feng
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Qin Liu
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Wen Zhang
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Qiuyun Chen
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Yi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China
| | - Xuebing Luo
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Donghua Xie
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Lizhu Luo
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
| | - Zhengjun Zhang
- Key Laboratory of Advanced Materials, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Xinchun Lai
- Science and Technology on Surface Physics and Chemistry Laboratory, Mianyang 621907, China
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9
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Iwasawa H, Shimada K, Schwier EF, Zheng M, Kojima Y, Hayashi H, Jiang J, Higashiguchi M, Aiura Y, Namatame H, Taniguchi M. Rotatable high-resolution ARPES system for tunable linear-polarization geometry. JOURNAL OF SYNCHROTRON RADIATION 2017; 24:836-841. [PMID: 28664891 PMCID: PMC5493027 DOI: 10.1107/s1600577517008037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 05/30/2017] [Indexed: 05/13/2023]
Abstract
A rotatable high-resolution angle-resolved photoemission spectroscopy (ARPES) system has been developed to utilize tunable linear-polarization geometries on the linear undulator beamline (BL-1) at Hiroshima Synchrotron Radiation Center. By rotating the whole ARPES measurement system, the photoelectron detection plane can be continuously changed from parallel to normal against the electric field vector of linearly polarized undulator radiation. This polarization tunability enables us to identify the symmetry of the initial electronic states with respect to the mirror planes, and to selectively observe the electronic states based on the dipole selection rule in the photoemission process. Specifications of the rotatable high-resolution ARPES system are described, as well as its capabilities with some representative experimental results.
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Affiliation(s)
- H. Iwasawa
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan
- Correspondence e-mail: ,
| | - K. Shimada
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan
- Correspondence e-mail: ,
| | - E. F. Schwier
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - M. Zheng
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Y. Kojima
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - H. Hayashi
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - J. Jiang
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - M. Higashiguchi
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
| | - Y. Aiura
- National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - H. Namatame
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - M. Taniguchi
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-0046, Japan
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10
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Kondo T, Ochi M, Nakayama M, Taniguchi H, Akebi S, Kuroda K, Arita M, Sakai S, Namatame H, Taniguchi M, Maeno Y, Arita R, Shin S. Orbital-Dependent Band Narrowing Revealed in an Extremely Correlated Hund's Metal Emerging on the Topmost Layer of Sr_{2}RuO_{4}. PHYSICAL REVIEW LETTERS 2016; 117:247001. [PMID: 28009182 DOI: 10.1103/physrevlett.117.247001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Indexed: 06/06/2023]
Abstract
We use a surface-selective angle-resolved photoemission spectroscopy and unveil the electronic nature on the topmost layer of Sr_{2}RuO_{4} crystal, consisting of slightly rotated RuO_{6} octahedrons. The γ band derived from the 4d_{xy} orbital is found to be about three times narrower than that for the bulk. This strongly contrasts with a subtle variation seen in the α and β bands derived from the one-dimensional 4d_{xz/yz}. This anomaly is reproduced by the dynamical mean-field theory calculations, introducing not only the on-site Hubbard interaction but also the significant Hund's coupling. We detect a coherence-to-incoherence crossover theoretically predicted for Hund's metals, which has been recognized only recently. The crossover temperature in the surface is about half that of the bulk, indicating that the naturally generated monolayer of reconstructed Sr_{2}RuO_{4} is extremely correlated and well isolated from the underlying crystal.
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Affiliation(s)
- Takeshi Kondo
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - M Ochi
- Department of Physics, Osaka University, Toyonaka, Osaka 560-0043, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - M Nakayama
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - H Taniguchi
- Department of Materials Science and Engineering, Iwate University, Morioka 020-8551, Japan
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - S Akebi
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - K Kuroda
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - M Arita
- Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - S Sakai
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - H Namatame
- Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
| | - M Taniguchi
- Hiroshima Synchrotron Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Y Maeno
- Department of Physics, Kyoto University, Kyoto 606-8502, Japan
| | - R Arita
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - S Shin
- ISSP, University of Tokyo, Kashiwa, Chiba 277-8581, Japan
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11
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Deng X, Haule K, Kotliar G. Transport Properties of Metallic Ruthenates: A DFT+DMFT Investigation. PHYSICAL REVIEW LETTERS 2016; 116:256401. [PMID: 27391734 DOI: 10.1103/physrevlett.116.256401] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Indexed: 06/06/2023]
Abstract
We present a systematical theoretical study on the transport properties of an archetypal family of Hund's metals, Sr_{2}RuO_{4}, Sr_{3}Ru_{2}O_{7}, SrRuO_{3}, and CaRuO_{3}, within the combination of first principles density functional theory and dynamical mean field theory. The agreement between theory and experiments for optical conductivity and resistivity is good, which indicates that electron-electron scattering dominates the transport of ruthenates. We demonstrate that in the single-site dynamical mean field approach the transport properties of Hund's metals fall into the scenario of "resilient quasiparticles." We explain why the single layered compound Sr_{2}RuO_{4} has a relative weak correlation with respect to its siblings, which corroborates its good metallicity.
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Affiliation(s)
- Xiaoyu Deng
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Kristjan Haule
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Gabriel Kotliar
- Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA
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12
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Jung SW, Shin WJ, Kim J, Moreschini L, Yeom HW, Rotenberg E, Bostwick A, Kim KS. Sublattice Interference as the Origin of σ Band Kinks in Graphene. PHYSICAL REVIEW LETTERS 2016; 116:186802. [PMID: 27203340 DOI: 10.1103/physrevlett.116.186802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Indexed: 06/05/2023]
Abstract
Kinks near the Fermi level observed in angle-resolved photoemission spectroscopy (ARPES) have been widely accepted to represent electronic coupling to collective excitations, but kinks at higher energies have eluded a unified description. We identify the mechanism leading to such kink features by means of ARPES and tight-binding band calculations on σ bands of graphene, where anomalous kinks at energies as high as ∼4 eV were reported recently [Phys. Rev. Lett. 111, 216806 (2013)]. We found that two σ bands show a strong intensity modulation with abruptly vanishing intensity near the kink features, which is due to sublattice interference. The interference induced local singularity in the matrix element is a critical factor that gives rise to apparent kink features, as confirmed by our spectral simulations without involving any coupling to collective excitations.
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Affiliation(s)
- Sung Won Jung
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Woo Jong Shin
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Jimin Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Luca Moreschini
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Han Woong Yeom
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Eli Rotenberg
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Aaron Bostwick
- Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Keun Su Kim
- Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang 37673, Korea
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
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'True' bosonic coupling strength in strongly correlated superconductors. Sci Rep 2013; 3:1930. [PMID: 23722675 PMCID: PMC3668320 DOI: 10.1038/srep01930] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 05/15/2013] [Indexed: 11/30/2022] Open
Abstract
Clarifying the coupling between electrons and bosonic excitations (phonons or magnetic fluctuations) that mediate the formation of Cooper pairs is pivotal to understand superconductivity. Such coupling effects are contained in the electron self-energy, which is experimentally accessible via angle-resolved photoemission spectroscopy (ARPES). However, in unconventional superconductors, identifying the nature of the electron-boson coupling remains elusive partly because of the significant band renormalization due to electron correlation. Until now, to quantify the electron-boson coupling, the self-energy is most often determined by assuming a phenomenological ‘bare’ band. Here, we demonstrate that the conventional procedure underestimates the electron-boson coupling depending on the electron-electron coupling, even if the self-energy appears to be self-consistent via the Kramers-Kronig relation. Our refined method explains well the electron-boson and electron-electron coupling strength in ruthenate superconductor Sr2RuO4, calling for a critical revision of the bosonic coupling strength from ARPES self-energy in strongly correlated electron systems.
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