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Arnoldi B, Zachritz SL, Hedwig S, Aeschlimann M, Monti OLA, Stadtmüller B. Revealing hidden spin polarization in centrosymmetric van der Waals materials on ultrafast timescales. Nat Commun 2024; 15:3573. [PMID: 38678075 PMCID: PMC11055871 DOI: 10.1038/s41467-024-47821-4] [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: 07/28/2023] [Accepted: 04/12/2024] [Indexed: 04/29/2024] Open
Abstract
One of the key challenges for spintronic and quantum technologies is to achieve active control of the spin angular momentum of electrons in nanoscale materials on ultrafast, femtosecond timescales. While conventional ferromagnetic materials and materials supporting spin texture suffer both from conceptional limitations in miniaturization and inefficiency of optical and electronic manipulation, non-magnetic centrosymmetric layered materials with hidden spin polarization may offer an alternative pathway to manipulate the spin degree of freedom by external stimuli. Here we demonstrate an approach for generating transient spin polarization on a femtosecond timescale in the otherwise spin-unpolarized band structure of the centrosymmetric 2H-stacked group VI transition metal dichalcogenide WSe2. Using ultrafast optical excitation of a fullerene layer grown on top of WSe2, we trigger an ultrafast interlayer electron transfer from the fullerene layer into the WSe2 crystal. The resulting transient charging of the C60/WSe2 interface leads to a substantial interfacial electric field that by means of spin-layer-valley locking ultimately creates ultrafast spin polarization without the need of an external magnetic field. Our findings open a novel pathway for true optical engineering of spin functionalities such as the sub-picosecond generation and manipulation of ultrafast spin currents in 2D heterostructures.
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Affiliation(s)
- B Arnoldi
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Erwin-Schroedinger-Strasse 46, Kaiserslautern, 67663, Germany
| | - S L Zachritz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - S Hedwig
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Erwin-Schroedinger-Strasse 46, Kaiserslautern, 67663, Germany
| | - M Aeschlimann
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Erwin-Schroedinger-Strasse 46, Kaiserslautern, 67663, Germany
| | - O L A Monti
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85721, USA.
- Department of Physics, University of Arizona, Tucson, AZ, 85721, USA.
| | - B Stadtmüller
- Department of Physics and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau, Erwin-Schroedinger-Strasse 46, Kaiserslautern, 67663, Germany.
- Institute of Physics, Johannes Gutenberg University Mainz, Staudingerweg 7, 55128, Mainz, Germany.
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2
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Zheng G, Zhu Y, Mozaffari S, Mao N, Chen KW, Jenkins K, Zhang D, Chan A, Arachchige HWS, Madhogaria RP, Cothrine M, Meier WR, Zhang Y, Mandrus D, Li L. Quantum oscillations evidence for topological bands in kagome metal ScV 6Sn 6. J Phys Condens Matter 2024; 36:215501. [PMID: 38335546 DOI: 10.1088/1361-648x/ad2803] [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] [Received: 12/13/2023] [Accepted: 02/09/2024] [Indexed: 02/12/2024]
Abstract
Metals with kagome lattice provide bulk materials to host both the flat-band and Dirac electronic dispersions. A new family of kagome metals is recently discovered inAV6Sn6. The Dirac electronic structures of this material needs more experimental evidence to confirm. In the manuscript, we investigate this problem by resolving the quantum oscillations in both electrical transport and magnetization in ScV6Sn6. The revealed orbits are consistent with the electronic band structure models. Furthermore, the Berry phase of a dominating orbit is revealed to be aroundπ, providing direct evidence for the topological band structure, which is consistent with calculations. Our results demonstrate a rich physics and shed light on the correlated topological ground state of this kagome metal.
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Affiliation(s)
- Guoxin Zheng
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Yuan Zhu
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Shirin Mozaffari
- Materials Science and Engineering Department, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
| | - Ning Mao
- Max Planck Institute for Chemical Physics of Solids, Dresden 01187, Germany
| | - Kuan-Wen Chen
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Kaila Jenkins
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Dechen Zhang
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Aaron Chan
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
| | - Hasitha W Suriya Arachchige
- Materials Science and Engineering Department, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
| | - Richa P Madhogaria
- Materials Science and Engineering Department, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
| | - Matthew Cothrine
- Materials Science and Engineering Department, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
| | - William R Meier
- Materials Science and Engineering Department, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
| | - Yang Zhang
- Department of Physics and Astronomy, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
- Min H. Kao Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN 37996, United States of America
| | - David Mandrus
- Materials Science and Engineering Department, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
- Department of Physics and Astronomy, University of Tennessee Knoxville, Knoxville, TN 37996, United States of America
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States of America
| | - Lu Li
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, United States of America
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3
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Chen R, Sun HP, Gu M, Hua CB, Liu Q, Lu HZ, Xie XC. Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators. Natl Sci Rev 2024; 11:nwac140. [PMID: 38264341 PMCID: PMC10804226 DOI: 10.1093/nsr/nwac140] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 01/25/2024] Open
Abstract
The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4 thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.
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Affiliation(s)
- Rui Chen
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Hai-Peng Sun
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, Würzburg 97074, Germany
| | - Mingqiang Gu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chun-Bo Hua
- School of Electronic and Information Engineering, Hubei University of Science and Technology, Xianning 437100, China
| | - Qihang Liu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Guangdong Provincial Key Laboratory of Computational Science and Material Design, Southern University of Science and Technology, Shenzhen 518055, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
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4
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Lin WC, Tsai PY, Zou JZ, Lee JY, Kuo CW, Lee HH, Pan CY, Yang CH, Chen SZ, Wang JS, Jiang PH, Liang CT, Chuang C. Chiral anomaly and Weyl orbit in three-dimensional Dirac semimetal Cd 3As 2grown on Si. Nanotechnology 2024; 35:165002. [PMID: 38154139 DOI: 10.1088/1361-6528/ad1941] [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] [Received: 10/06/2023] [Accepted: 12/27/2023] [Indexed: 12/30/2023]
Abstract
Preparing Cd3As2, which is a three-dimensional (3D) Dirac semimetal in certain crystal orientation, on Si is highly desirable as such a sample may well be fully compatible with existing Si CMOS technology. However, there is a dearth of such a study regarding Cd3As2films grown on Si showing the chiral anomaly. Here,for the first time, we report the novel preparation and fabrication technique of a Cd3As2(112) film on a Si (111) substrate with a ZnTe (111) buffer layer which explicitly shows the chiral anomaly with a nontrivial Berry's phase ofπ. Despite the Hall carrier density (n3D≈9.42×1017cm-3) of our Cd3As2film, which is almost beyond the limit for the portents of a 3D Dirac semimetal to emerge, we observe large linear magnetoresistance in a perpendicular magnetic field and negative magnetoresistance in a parallel magnetic field. These results clearly demonstrate the chiral magnetic effect and 3D Dirac semimetallic behavior in our silicon-based Cd3As2film. Our tailoring growth of Cd3As2on a conventional substrate such as Si keeps the sample quality, while also achieving a low carrier concentration.
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Affiliation(s)
- Wei-Chen Lin
- Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan
| | - Peng-Ying Tsai
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
| | - Jia-Zhu Zou
- National Taiwan University, Taipei 106, Taiwan
| | | | - Chun-Wei Kuo
- Department of Electronic Engineering, Chung Yuan Christian University, Taoyuan 320, Taiwan
| | - Hsin-Hsuan Lee
- Department of Physics, Chung Yuan Christian University, Taoyuan 320, Taiwan
| | - Ching-Yang Pan
- Department of Physics, National Taiwan Normal University 106, Taiwan
| | - Cheng-Hsueh Yang
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
| | | | - Jyh-Shyang Wang
- Department of Physics, Chung Yuan Christian University, Taoyuan 320, Taiwan
- Research Center for Semiconductor Materials and Advanced Optics, Chung Yuan Christian University, Taoyuan, 320, Taiwan
| | - Pei-Hsun Jiang
- Department of Physics, National Taiwan Normal University 106, Taiwan
| | - Chi-Te Liang
- Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan
- National Taiwan University, Taipei 106, Taiwan
| | - Chiashain Chuang
- Department of Electronic Engineering, Chung Yuan Christian University, Taoyuan 320, Taiwan
- Research Center for Semiconductor Materials and Advanced Optics, Chung Yuan Christian University, Taoyuan, 320, Taiwan
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5
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Rocchino L, Balduini F, Schmid H, Molinari A, Luisier M, Süß V, Felser C, Gotsmann B, Zota CB. Magnetoresistive-coupled transistor using the Weyl semimetal NbP. Nat Commun 2024; 15:710. [PMID: 38267457 DOI: 10.1038/s41467-024-44961-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 01/04/2024] [Indexed: 01/26/2024] Open
Abstract
Semiconductor transistors operate by modulating the charge carrier concentration of a channel material through an electric field coupled by a capacitor. This mechanism is constrained by the fundamental transport physics and material properties of such devices-attenuation of the electric field, and limited mobility and charge carrier density in semiconductor channels. In this work, we demonstrate a new type of transistor that operates through a different mechanism. The channel material is a Weyl semimetal, NbP, whose resistivity is modulated via a magnetic field generated by an integrated superconductor. Due to the exceptionally large electron mobility of this material, which reaches over 1,000,000 cm2/Vs, and the strong magnetoresistive coupling, the transistor can generate significant transconductance amplification at nanowatt levels of power. This type of device can enable new low-power amplifiers, suitable for qubit readout operation in quantum computers.
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Affiliation(s)
- Lorenzo Rocchino
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland.
| | - Federico Balduini
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | - Heinz Schmid
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | - Alan Molinari
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | | | - Vicky Süß
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187, Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187, Dresden, Germany
| | - Bernd Gotsmann
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
| | - Cezar B Zota
- IBM Research Europe-Zürich, Saümerstrasse 4, 8803, Rüschlikon, Switzerland
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6
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Niu C, Qiu G, Wang Y, Tan P, Wang M, Jian J, Wang H, Wu W, Ye PD. Tunable Chirality-Dependent Nonlinear Electrical Responses in 2D Tellurium. Nano Lett 2023; 23:8445-8453. [PMID: 37677143 DOI: 10.1021/acs.nanolett.3c01797] [Citation(s) in RCA: 1] [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] [Indexed: 09/09/2023]
Abstract
Tellurium (Te) is an elemental semiconductor with a simple chiral crystal structure. Te in a two-dimensional (2D) form synthesized by a solution-based method shows excellent electrical, optical, and thermal properties. In this work, the chirality of hydrothermally grown 2D Te is identified and analyzed by hot sulfuric acid etching and high-angle tilted high-resolution scanning transmission electron microscopy. The gate-tunable nonlinear electrical responses, including the nonreciprocal electrical transport in the longitudinal direction and the nonlinear planar Hall effect in the transverse direction, are observed in 2D Te under a magnetic field. Moreover, the nonlinear electrical responses have opposite signs in left- and right-handed 2D Te due to the opposite spin polarizations ensured by the chiral symmetry. The fundamental relationship between the spin-orbit coupling and the crystal symmetry in two enantiomers provides a viable platform for realizing chirality-based electronic devices by introducing the degree of freedom of chirality into electron transport.
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Affiliation(s)
- Chang Niu
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Gang Qiu
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yixiu Wang
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Pukun Tan
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
| | - Mingyi Wang
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jie Jian
- School of Materials Science and Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Haiyan Wang
- School of Materials Science and Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Wenzhuo Wu
- School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Peide D Ye
- Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, United States
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States
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7
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Siegfried PE, Bhandari H, Qi J, Ghimire R, Joshi J, Messegee ZT, Beeson WB, Liu K, Ghimire MP, Dang Y, Zhang H, Davydov AV, Tan X, Vora PM, Mazin II, Ghimire NJ. CoTe 2 : A Quantum Critical Dirac Metal with Strong Spin Fluctuations. Adv Mater 2023; 35:e2300640. [PMID: 37012602 DOI: 10.1002/adma.202300640] [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: 01/19/2023] [Indexed: 05/26/2023]
Abstract
Quantum critical points separating weak ferromagnetic and paramagnetic phases trigger many novel phenomena. Dynamical spin fluctuations not only suppress the long-range order, but can also lead to unusual transport and even superconductivity. Combining quantum criticality with topological electronic properties presents a rare and unique opportunity. Here, by means of ab initio calculations and magnetic, thermal, and transport measurements, it is shown that the orthorhombic CoTe2 is close to ferromagnetism, which appears suppressed by spin fluctuations. Calculations and transport measurements reveal nodal Dirac lines, making it a rare combination of proximity to quantum criticality and Dirac topology.
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Affiliation(s)
- Peter E Siegfried
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
| | - Hari Bhandari
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
| | - Jeanie Qi
- Thomas Jefferson High School, Alexandria, VA, 22312, USA
| | - Rojila Ghimire
- Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal
| | - Jayadeep Joshi
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
| | - Zachary T Messegee
- Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA, 22030, USA
| | - Willie B Beeson
- Physics Department, Georgetown University, Washington, DC, 20057, USA
| | - Kai Liu
- Physics Department, Georgetown University, Washington, DC, 20057, USA
| | - Madhav Prasad Ghimire
- Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, 44613, Nepal
| | - Yanliu Dang
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, 20899, USA
| | - Huairuo Zhang
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, 20899, USA
- Theiss Research, Inc., La Jolla, CA, 92037, USA
| | - Albert V Davydov
- Materials Science and Engineering Division, National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, 20899, USA
| | - Xiaoyan Tan
- Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA, 22030, USA
| | - Patrick M Vora
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
| | - Igor I Mazin
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
| | - Nirmal J Ghimire
- Department of Physics and Astronomy, George Mason University, Fairfax, VA, 22030, USA
- Quantum Science and Engineering Center, George Mason University, Fairfax, VA, 22030, USA
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8
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Gao W, Zhu M, Chen D, Liang X, Wu Y, Zhu A, Han Y, Li L, Liu X, Zheng G, Lu W, Tian M. Evidences of Topological Surface States in the Nodal-Line Semimetal SnTaS 2 Nanoflakes. ACS Nano 2023; 17:4913-4921. [PMID: 36802534 DOI: 10.1021/acsnano.2c11932] [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: 06/18/2023]
Abstract
Exploring the topological surface state of a topological semimetal by the transport technique has always been a big challenge because of the overwhelming contribution of the bulk state. In this work, we perform systematic angular-dependent magnetotransport measurements and electronic band calculations on SnTaS2 crystals, a layered topological nodal-line semimetal. Distinct Shubnikov-de Haas quantum oscillations were observed only in SnTaS2 nanoflakes when the thickness was below about 110 nm, and the oscillation amplitudes increased significantly with decreasing thickness. By analysis of the oscillation spectra, together with the theoretical calculation, a two-dimensional and topological nontrivial nature of the surface band is unambiguously identified, providing direct transport evidence of drumhead surface state for SnTaS2. Our comprehensive understanding of the Fermi surface topology of the centrosymmetric superconductor SnTaS2 is crucial for further research on the interplay of superconductivity and nontrivial topology.
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Affiliation(s)
- Wenshuai Gao
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Mengcheng Zhu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Dong Chen
- College of Physics, Qingdao University, Qingdao 266071, China
| | - Xin Liang
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Yuelong Wu
- College of Physics, Qingdao University, Qingdao 266071, China
| | - Ankang Zhu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Yuyan Han
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Liang Li
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Xue Liu
- Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China
| | - Guolin Zheng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
| | - Wenjian Lu
- Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China
| | - Mingliang Tian
- School of Physics and Optoelectronics Engineering, Anhui University, Hefei 230601, China
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, China
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9
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Xu X, Yin JX, Ma W, Tien HJ, Qiang XB, Reddy PVS, Zhou H, Shen J, Lu HZ, Chang TR, Qu Z, Jia S. Topological charge-entropy scaling in kagome Chern magnet TbMn6Sn6. Nat Commun 2022; 13:1197. [PMID: 35256604 PMCID: PMC8901788 DOI: 10.1038/s41467-022-28796-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 01/26/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractIn ordinary materials, electrons conduct both electricity and heat, where their charge-entropy relations observe the Mott formula and the Wiedemann-Franz law. In topological quantum materials, the transverse motion of relativistic electrons can be strongly affected by the quantum field arising around the topological fermions, where a simple model description of their charge-entropy relations remains elusive. Here we report the topological charge-entropy scaling in the kagome Chern magnet TbMn6Sn6, featuring pristine Mn kagome lattices with strong out-of-plane magnetization. Through both electric and thermoelectric transports, we observe quantum oscillations with a nontrivial Berry phase, a large Fermi velocity and two-dimensionality, supporting the existence of Dirac fermions in the magnetic kagome lattice. This quantum magnet further exhibits large anomalous Hall, anomalous Nernst, and anomalous thermal Hall effects, all of which persist to above room temperature. Remarkably, we show that the charge-entropy scaling relations of these anomalous transverse transports can be ubiquitously described by the Berry curvature field effects in a Chern-gapped Dirac model. Our work points to a model kagome Chern magnet for the proof-of-principle elaboration of the topological charge-entropy scaling.
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10
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Huang SM, Wang PC, Chen PC, Hong JL, Cheng CM, Jian HL, Yan YJ, Yu SH, Chou MMC. The Singularity Paramagnetic Peak of Bi 0.3Sb 1.7Te 3 with p-type Surface State. Nanoscale Res Lett 2022; 17:12. [PMID: 35032238 PMCID: PMC8761187 DOI: 10.1186/s11671-021-03650-8] [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] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 12/30/2021] [Indexed: 06/14/2023]
Abstract
The magnetization measurement was performed in the Bi0.3Sb1.7Te3 single crystal. The magnetic susceptibility revealed a paramagnetic peak independent of the experimental temperature variation. It is speculated to be originated from the free-aligned spin texture at the Dirac point. The ARPES reveals that the Fermi level lies below the Dirac point. The Fermi wavevector extracted from the de Haas-van Alphen oscillation is consistent with the energy dispersion in the ARPES. Our experimental results support that the observed paramagnetic peak in the susceptibility curve does not originate from the free-aligned spin texture at the Dirac point.
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Affiliation(s)
- Shiu-Ming Huang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, TCECM, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
- Center of Crystal Research, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - Pin-Cing Wang
- Department of Physics, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - Pin-Cyuan Chen
- Department of Physics, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - Jai-Long Hong
- Department of Physics, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - Cheng-Maw Cheng
- National Synchrotron Radiation Research Center, Hsin-Chiu, 80076 Taiwan
| | - Hao-Lun Jian
- Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - You-Jhih Yan
- Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - Shih-Hsun Yu
- Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
| | - Mitch M. C. Chou
- Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, TCECM, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
- Center of Crystal Research, National Sun Yat-Sen University, Kaohsiung, 80424 Taiwan
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11
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Howlader S, Sheet G. Tip-induced superconductivity. J Phys Condens Matter 2021; 33:403002. [PMID: 34087817 DOI: 10.1088/1361-648x/ac0850] [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] [Received: 01/13/2021] [Accepted: 06/04/2021] [Indexed: 06/12/2023]
Abstract
It is widely believed that topological superconductivity, a hitherto elusive phase of quantum matter, can be achieved by inducing superconductivity in topological materials. In search of such topological superconductors, certain topological insulators (like, Bi2Se3) were successfully turned into superconductors by metal-ion (Cu, Pd, Sr, Nb etc) intercalation. Superconductivity could be induced in topological materials through applying pressure as well. For example, a pressure-induced superconducting phase was found in the topological insulator Bi2Se3. However, in all such cases, no conclusive signature of topological superconductivity was found. In this review, we will discuss about another novel way of inducing superconductivity in a non-superconducting topological material-by creating a mesoscopic interface on the material with a non-superconducting, normal metallic tip where the mesoscopic interface becomes superconducting. Such a phase is now known as a tip-induced superconducting (TISC) phase. This was first realized on Cd3As2in India. Following that, a large number of other topological materials were shown to display TISC. Since the TISC phase emerges only at a confined region under a mesoscopic point contact, traditional bulk tools for characterizing superconductivity cannot be employed to detect/confirm such a phase. On the other hand, such a point contact geometry is ideal for probing the possible existence of a temperature and magnetic field dependent superconducting energy gap and a temperature and magnetic field dependent critical current. We will review the details of the experimental signatures that can be used to prove the existence of superconductivity even when the 'text-book' tests for detecting superconductivity cannot be performed. Then, we will review various systems where a TISC phase could be realized.
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Affiliation(s)
- Sandeep Howlader
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, 81, Knowledge City, SAS Nagar, Manauli 140306, Punjab, India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, 81, Knowledge City, SAS Nagar, Manauli 140306, Punjab, India
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12
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Ma W, Xu X, Yin JX, Yang H, Zhou H, Cheng ZJ, Huang Y, Qu Z, Wang F, Hasan MZ, Jia S. Rare Earth Engineering in RMn_{6}Sn_{6} (R=Gd-Tm, Lu) Topological Kagome Magnets. Phys Rev Lett 2021; 126:246602. [PMID: 34213939 DOI: 10.1103/physrevlett.126.246602] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 05/20/2021] [Indexed: 05/25/2023]
Abstract
Exploration of the topological quantum materials with electron correlation is at the frontier of physics, as the strong interaction may give rise to new topological phases and transitions. Here we report that a family of kagome magnets RMn_{6}Sn_{6} manifest the quantum transport properties analogical to those in the quantum-limit Chern magnet TbMn_{6}Sn_{6}. The topological transport in the family, including quantum oscillations with nontrivial Berry phase and large anomalous Hall effect arising from Berry curvature field, points to the existence of Chern gapped Dirac fermions. Our observation demonstrates a close relationship between rare-earth magnetism and topological electron structure, indicating the rare-earth elements can effectively engineer the Chern quantum phase in kagome magnets.
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Affiliation(s)
- Wenlong Ma
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Xitong Xu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Jia-Xin Yin
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Hui Yang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Huibin Zhou
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Zi-Jia Cheng
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yuqing Huang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Zhe Qu
- Anhui Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei, Anhui 230031, China
- CAS Key Laboratory of Photovoltaic and Energy Conservation Materials, Hefei Institutes of Physical Sciences, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Fa Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - M Zahid Hasan
- Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Beijing Academy of Quantum Information Sciences, West Building 3, No. 10 Xibeiwang East Road, Haidian District, Beijing 100193, China
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13
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Abstract
Recently, it was pointed out that all chiral crystals with spin-orbit coupling (SOC) can be Kramers Weyl semimetals (KWSs) which possess Weyl points pinned at time-reversal invariant momenta. In this work, we show that all achiral non-centrosymmetric materials with SOC can be a new class of topological materials, which we term Kramers nodal line metals (KNLMs). In KNLMs, there are doubly degenerate lines, which we call Kramers nodal lines (KNLs), connecting time-reversal invariant momenta. The KNLs create two types of Fermi surfaces, namely, the spindle torus type and the octdong type. Interestingly, all the electrons on octdong Fermi surfaces are described by two-dimensional massless Dirac Hamiltonians. These materials support quantized optical conductance in thin films. We further show that KNLMs can be regarded as parent states of KWSs. Therefore, we conclude that all non-centrosymmetric metals with SOC are topological, as they can be either KWSs or KNLMs.
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Affiliation(s)
- Ying-Ming Xie
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Xue-Jian Gao
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Xiao Yan Xu
- Department of Physics, University of California at San Diego, La Jolla, CA, USA
| | - Cheng-Ping Zhang
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jin-Xin Hu
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jason Z Gao
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - K T Law
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China.
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14
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Sheng F, Hua C, Cheng M, Hu J, Sun X, Tao Q, Lu H, Lu Y, Zhong M, Watanabe K, Taniguchi T, Xia Q, Xu ZA, Zheng Y. Rashba valleys and quantum Hall states in few-layer black arsenic. Nature 2021; 593:56-60. [PMID: 33953409 DOI: 10.1038/s41586-021-03449-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/11/2021] [Indexed: 11/09/2022]
Abstract
Exciting phenomena may emerge in non-centrosymmetric two-dimensional electronic systems when spin-orbit coupling (SOC)1 interplays dynamically with Coulomb interactions2,3, band topology4,5 and external modulating forces6-8. Here we report synergetic effects between SOC and the Stark effect in centrosymmetric few-layer black arsenic, which manifest as particle-hole asymmetric Rashba valley formation and exotic quantum Hall states that are reversibly controlled by electrostatic gating. The unusual findings are rooted in the puckering square lattice of black arsenic, in which heavy 4p orbitals form a Brillouin zone-centred Γ valley with pz symmetry, coexisting with doubly degenerate D valleys of px origin near the time-reversal-invariant momenta of the X points. When a perpendicular electric field breaks the structure inversion symmetry, strong Rashba SOC is activated for the px bands, which produces spin-valley-flavoured D± valleys paired by time-reversal symmetry, whereas Rashba splitting of the Γ valley is constrained by the pz symmetry. Intriguingly, the giant Stark effect shows the same px-orbital selectiveness, collectively shifting the valence band maximum of the D± Rashba valleys to exceed the Γ Rashba top. Such an orchestrating effect allows us to realize gate-tunable Rashba valley manipulations for two-dimensional hole gases, hallmarked by unconventional even-to-odd transitions in quantum Hall states due to the formation of a flavour-dependent Landau level spectrum. For two-dimensional electron gases, the quantization of the Γ Rashba valley is characterized by peculiar density-dependent transitions in the band topology from trivial parabolic pockets to helical Dirac fermions.
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Affiliation(s)
- Feng Sheng
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Chenqiang Hua
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Man Cheng
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Jie Hu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Xikang Sun
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Qian Tao
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Hengzhe Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Yunhao Lu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China
| | - Mianzeng Zhong
- School of Physics and Electronics, Hunan Key Laboratory of Nanophotonics and Devices, Central South University, Changsha, People's Republic of China
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | | | - Qinglin Xia
- School of Physics and Electronics, Hunan Key Laboratory of Nanophotonics and Devices, Central South University, Changsha, People's Republic of China.
| | - Zhu-An Xu
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China. .,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, People's Republic of China.
| | - Yi Zheng
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou, People's Republic of China. .,State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, People's Republic of China.
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15
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Han F, Andrejevic N, Nguyen T, Kozii V, Nguyen QT, Hogan T, Ding Z, Pablo-Pedro R, Parjan S, Skinner B, Alatas A, Alp E, Chi S, Fernandez-Baca J, Huang S, Fu L, Li M. Quantized thermoelectric Hall effect induces giant power factor in a topological semimetal. Nat Commun 2020; 11:6167. [PMID: 33268778 PMCID: PMC7710760 DOI: 10.1038/s41467-020-19850-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [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: 07/02/2020] [Accepted: 11/03/2020] [Indexed: 11/24/2022] Open
Abstract
Thermoelectrics are promising by directly generating electricity from waste heat. However, (sub-)room-temperature thermoelectrics have been a long-standing challenge due to vanishing electronic entropy at low temperatures. Topological materials offer a new avenue for energy harvesting applications. Recent theories predicted that topological semimetals at the quantum limit can lead to a large, non-saturating thermopower and a quantized thermoelectric Hall conductivity approaching a universal value. Here, we experimentally demonstrate the non-saturating thermopower and quantized thermoelectric Hall effect in the topological Weyl semimetal (WSM) tantalum phosphide (TaP). An ultrahigh longitudinal thermopower \documentclass[12pt]{minimal}
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\begin{document}$$\sim 525 \, \mu \, {\mathrm{W}} \, {\mathrm{cm}}^{ - 1} \, {\mathrm{K}}^{ - 2}$$\end{document}~525μWcm−1K−2 are observed at ~40 K, which is largely attributed to the quantized thermoelectric Hall effect. Our work highlights the unique quantized thermoelectric Hall effect realized in a WSM toward low-temperature energy harvesting applications. Theories predict a large thermopower and a quantized thermoelectric Hall conductivity in topological semimetals. Here, the authors observe an ultrahigh longitudinal thermopower and a giant power factor attributed to the quantized thermoelectric Hall effect in a Weyl semimetal TaP.
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Affiliation(s)
- Fei Han
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Nina Andrejevic
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Thanh Nguyen
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Vladyslav Kozii
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Quynh T Nguyen
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Tom Hogan
- Quantum Design, Inc., San Diego, CA, 92121, USA
| | - Zhiwei Ding
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ricardo Pablo-Pedro
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Shreya Parjan
- Department of Physics, Wellesley College, Wellesley, MA, 02481, USA
| | - Brian Skinner
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ahmet Alatas
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Ercan Alp
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Songxue Chi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Jaime Fernandez-Baca
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Shengxi Huang
- Department of Electrical Engineering, The Pennsylvania State University, State College, PA, 16802, USA
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| | - Mingda Li
- Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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16
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Capolupo A, Giampaolo SM, Lambiase G, Quaranta A. Discerning the Nature of Neutrinos: Decoherence and Geometric Phases. Universe 2020; 6:207. [DOI: 10.3390/universe6110207] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We present new approaches to distinguish between Dirac and Majorana neutrinos. The first is based on the analysis of the geometric phases associated to neutrinos in matter, the second on the effects of decoherence on neutrino oscillations. In the former we compute the total and geometric phase for neutrinos, and find that they depend on the Majorana phase and on the parametrization of the mixing matrix. In the latter, we show that Majorana neutrinos might violate CPT symmetry, whereas Dirac neutrinos preserve CPT. A phenomenological analysis is also reported showing the possibility to highlight the distinctions between Dirac and Majorana neutrinos.
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17
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Takiguchi K, Wakabayashi YK, Irie H, Krockenberger Y, Otsuka T, Sawada H, Nikolaev SA, Das H, Tanaka M, Taniyasu Y, Yamamoto H. Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide. Nat Commun 2020; 11:4969. [PMID: 33037206 DOI: 10.1038/s41467-020-18646-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 09/06/2020] [Indexed: 11/13/2022] Open
Abstract
Magnetic Weyl semimetals have novel transport phenomena related to pairs of Weyl nodes in the band structure. Although the existence of Weyl fermions is expected in various oxides, the evidence of Weyl fermions in oxide materials remains elusive. Here we show direct quantum transport evidence of Weyl fermions in an epitaxial 4d ferromagnetic oxide SrRuO3. We employ machine-learning-assisted molecular beam epitaxy to synthesize SrRuO3 films whose quality is sufficiently high to probe their intrinsic transport properties. Experimental observation of the five transport signatures of Weyl fermions—the linear positive magnetoresistance, chiral-anomaly-induced negative magnetoresistance, π phase shift in a quantum oscillation, light cyclotron mass, and high quantum mobility of about 10,000 cm2V−1s−1—combined with first-principles electronic structure calculations establishes SrRuO3 as a magnetic Weyl semimetal. We also clarify the disorder dependence of the transport of the Weyl fermions, which gives a clear guideline for accessing the topologically nontrivial transport phenomena. Despite various predictions, the evidence of Weyl fermions in oxide materials remains elusive. Here, the authors show evidence of Weyl fermions in quantum transport measurements in an epitaxial ferromagnetic oxide SrRuO3.
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18
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Nagpal V, Patnaik S. Breakdown of Ohm's law and nontrivial Berry phase in magnetic Weyl semimetal Co 3Sn 2S 2. J Phys Condens Matter 2020; 32:405602. [PMID: 32480388 DOI: 10.1088/1361-648x/ab9859] [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] [Indexed: 06/11/2023]
Abstract
The concept of realization of Weyl points close to the Fermi level in materials with broken time-reversal symmetry has significant theoretical and technological ramifications. Here, we review the investigation of magneto-transport measurements in single crystals of magnetic Weyl semimetal Co3Sn2S2. We see a turn-on like behaviour followed by saturation in resistivity under magnetic field in the low temperature region which is allocated to the topological surface states. A non-saturating magnetoresistance, linear at high fields, is observed at low temperatures where applied magnetic field is transverse to the current direction. The linear negative magnetoresistance at low magnetic fields (B < 0.1 T) provides evidence for time reversal symmetry breaking in Co3Sn2S2. Chiral anomaly in Weyl metallic state in Co3Sn2S2 is confirmed from the breakdown of Ohm's law in the electronic transport. Shubnikov de Haas (SdH) oscillation measurement has unveiled the multiple sub-bands on the Fermi surface that corresponds to a non-trivial Berry phase. The non-linear behaviour in Hall resistivity validates the existence of two type of charge carriers with equal electron and hole densities. Strong temperature dependence of carrier mobilities reflects the systematic violation of Kohler's rule in Co3Sn2S2. Our findings open avenues to study kagome-lattice based magnetic Weyl semimetals that unfurl the basic topological aspects leading to significant ramification for spintronics.
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Affiliation(s)
- V Nagpal
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067, Delhi, India
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19
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Maruhashi K, Takahashi KS, Bahramy MS, Shimizu S, Kurihara R, Miyake A, Tokunaga M, Tokura Y, Kawasaki M. Anisotropic Quantum Transport through a Single Spin Channel in the Magnetic Semiconductor EuTiO 3. Adv Mater 2020; 32:e1908315. [PMID: 32383210 DOI: 10.1002/adma.201908315] [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] [Received: 12/18/2019] [Revised: 03/12/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Magnetic semiconductors are a vital component in the understanding of quantum transport phenomena. To explore such delicate, yet fundamentally important, effects, it is crucial to maintain a high carrier mobility in the presence of magnetic moments. In practice, however, magnetization often diminishes the carrier mobility. Here, it is shown that EuTiO3 is a rare example of a magnetic semiconductor that can be desirably grown using the molecular beam epitaxy to possess a high carrier mobility exceeding 3000 cm2 V-1 s-1 at 2 K, while intrinsically hosting a large magnetization value, 7 μB per formula unit. This is demonstrated by measuring the Shubnikov-de Haas (SdH) oscillations in the ferromagnetic state of EuTiO3 films with various carrier densities. Using first-principles calculations, it is shown that the observed SdH oscillations originate genuinely from Ti 3d-t2g states which are fully spin-polarized due to their energetical proximity to the in-gap Eu 4f bands. Such an exchange coupling is further shown to have a profound effect on the effective mass and fermiology of the Ti 3d-t2g electrons, manifested by a directional anisotropy in the SdH oscillations. These findings suggest that EuTiO3 film is an ideal magnetic semiconductor, offering a fertile field to explore quantum phenomena suitable for spintronic applications.
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Affiliation(s)
- Kazuki Maruhashi
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
| | - Kei S Takahashi
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo, 102-0075, Japan
| | - Mohammad Saeed Bahramy
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Sunao Shimizu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Ryosuke Kurihara
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Atsushi Miyake
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Masashi Tokunaga
- Institute for Solid State Physics, University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Yoshinori Tokura
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Masashi Kawasaki
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
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20
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Wadehra N, Tomar R, Varma RM, Gopal RK, Singh Y, Dattagupta S, Chakraverty S. Planar Hall effect and anisotropic magnetoresistance in polar-polar interface of LaVO 3-KTaO 3 with strong spin-orbit coupling. Nat Commun 2020; 11:874. [PMID: 32054860 PMCID: PMC7018836 DOI: 10.1038/s41467-020-14689-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [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: 06/11/2019] [Accepted: 01/23/2020] [Indexed: 11/26/2022] Open
Abstract
Among the perovskite oxide family, KTaO3 (KTO) has recently attracted considerable interest as a possible system for the realization of the Rashba effect. In this work, we report a novel conducting interface by placing KTO with another insulator, LaVO3 (LVO) and report planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) measurements. This interface exhibits a signature of strong spin-orbit coupling. Our experimental observations of two fold AMR and PHE at low magnetic fields (B) is similar to those obtained for topological systems and can be intuitively understood using a phenomenological theory for a Rashba spin-split system. Our experimental data show a B2 dependence of AMR and PHE at low magnetic fields that could also be explained based on our model. At high fields (~8 T), we see a two fold to four fold transition in the AMR that could not be explained using only Rashba spin-split energy spectra. Two dimensional electron gas (2DEG) at oxide interfaces is promising in modern electronic devices. Here, Wadehra et al. realize 2DEG at a novel interface composed of LaVO3 and KTaO3, where strong spin-orbit coupling and relativistic nature of the electrons in the 2DEG, leading to anisotropic magnetoresistance and planar Hall effect.
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Affiliation(s)
- Neha Wadehra
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India
| | - Ruchi Tomar
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India
| | - Rahul Mahavir Varma
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangaluru, Karnataka, 560012, India
| | - R K Gopal
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Manauli, 140306, India
| | - Yogesh Singh
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector-81, SAS Nagar, Manauli, 140306, India
| | - Sushanta Dattagupta
- Bose Institute, P-1/12, CIT Rd, Scheme VIIM, Kankurgachi, Kolkata, West Bengal, 700054, India
| | - S Chakraverty
- Nanoscale Physics and Device Laboratory, Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab, 160062, India.
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21
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Ideue T, Hirayama M, Taiko H, Takahashi T, Murase M, Miyake T, Murakami S, Sasagawa T, Iwasa Y. Pressure-induced topological phase transition in noncentrosymmetric elemental tellurium. Proc Natl Acad Sci U S A 2019; 116:25530-25534. [PMID: 31801879 PMCID: PMC6926023 DOI: 10.1073/pnas.1905524116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [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
Recent progress in understanding the electronic band topology and emergent topological properties encourage us to reconsider the band structure of well-known materials including elemental substances. Controlling such a band topology by external field is of particular interest from both fundamental and technological viewpoints. Here we report possible signatures of the pressure-induced topological phase transition from a semiconductor to a Weyl semimetal in elemental tellurium probed by transport measurements. Pressure variation of the periods of Shubnikov-de Haas oscillations, as well as oscillation phases, shows an anomaly around the pressure theoretically predicted for topological phase transition. This behavior is consistent with the pressure-induced band deformation and resultant band-crossing effect. Moreover, effective cyclotron mass is reduced toward the critical pressure, potentially reflecting the emergence of massless linear dispersion. The present result paves the way for studying the electronic band topology in well-known compounds and topological phase transition by the external field.
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Affiliation(s)
- Toshiya Ideue
- Quantum-Phase Electronics Center, The University of Tokyo, 113-8656 Tokyo, Japan;
| | - Motoaki Hirayama
- RIKEN Center for Emergent Matter Science (CEMS), 351-0198 Wako, Japan
| | - Hiroaki Taiko
- Department of Applied Physics, The University of Tokyo, 113-8656 Tokyo, Japan
| | - Takanari Takahashi
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, 226-8503 Kanagawa, Japan
| | - Masayuki Murase
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, 226-8503 Kanagawa, Japan
| | - Takashi Miyake
- Research Center for Computational Design of Advanced Functional Materials, National Institute of Advanced Industrial Science and Technology, 305-8568 Tsukuba, Japan
| | - Shuichi Murakami
- Department of Physics, Tokyo Institute of Technology, 152-8551 Tokyo, Japan
- Tokodai Institute for Element Strategy, Tokyo Institute of Technology, 152-8551 Tokyo, Japan
| | - Takao Sasagawa
- Laboratory for Materials and Structures, Tokyo Institute of Technology, Yokohama, 226-8503 Kanagawa, Japan
| | - Yoshihiro Iwasa
- Quantum-Phase Electronics Center, The University of Tokyo, 113-8656 Tokyo, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 351-0198 Wako, Japan
- Department of Applied Physics, The University of Tokyo, 113-8656 Tokyo, Japan
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22
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Izaki Y, Fuseya Y. Nonperturbative Matrix Mechanics Approach to Spin-Split Landau Levels and the g Factor in Spin-Orbit Coupled Solids. Phys Rev Lett 2019; 123:156403. [PMID: 31702292 DOI: 10.1103/physrevlett.123.156403] [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: 06/30/2019] [Indexed: 06/10/2023]
Abstract
We propose a fully quantum approach to nonperturbatively calculate the spin-split Landau levels and g factor of various spin-orbit coupled solids based on the k·p theory in the matrix mechanics representation. The new method considers the detailed band structure and the multiband effect of spin-orbit coupling irrespective of the magnetic-field strength. We show an application of this method to PbTe, a typical Dirac electron system. Contrary to popular belief, we show that the spin-splitting parameter M, which is the ratio of the Zeeman to cyclotron energy, exhibits a remarkable magnetic-field dependence. This field dependence can rectify the existing discrepancy between experimental and theoretical results. We also show that M evaluated from the fan diagram plot is different from that determined as the ratio of the Zeeman to cyclotron energy, which also overturns common belief.
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Affiliation(s)
- Yuki Izaki
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Yuki Fuseya
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
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23
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Datta B, Adak PC, Shi LK, Watanabe K, Taniguchi T, Song JCW, Deshmukh MM. Nontrivial quantum oscillation geometric phase shift in a trivial band. Sci Adv 2019; 5:eaax6550. [PMID: 31667347 PMCID: PMC6799982 DOI: 10.1126/sciadv.aax6550] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 09/20/2019] [Indexed: 06/10/2023]
Abstract
Quantum oscillations provide a notable visualization of the Fermi surface of metals, including associated geometrical phases such as Berry's phase, that play a central role in topological quantum materials. Here we report the existence of a new quantum oscillation phase shift in a multiband system. In particular, we study the ABA-trilayer graphene, the band structure of which is composed of a weakly gapped linear Dirac band, nested within a quadratic band. We observe that Shubnikov-de Haas (SdH) oscillations of the quadratic band are shifted by a phase that sharply departs from the expected 2π Berry's phase and is inherited from the nontrivial Berry's phase of the linear band. We find this arises due to an unusual filling enforced constraint between the quadratic band and linear band Fermi surfaces. Our work indicates how additional bands can be exploited to tease out the effect of often subtle quantum mechanical geometric phases.
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Affiliation(s)
- Biswajit Datta
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Pratap Chandra Adak
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Li-kun Shi
- Institute of High Performance Computing, Agency for Science, Technology, and Research, Singapore 138632, Singapore
| | - Kenji Watanabe
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Justin C. W. Song
- Institute of High Performance Computing, Agency for Science, Technology, and Research, Singapore 138632, Singapore
- Division of Physics and Applied Physics, Nanyang Technological University, Singapore 637371, Singapore
| | - Mandar M. Deshmukh
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
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24
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Bobin SB, Lonchakov AT, Deryushkin VV, Neverov VN. Nontrivial topology of bulk HgSe from the study of cyclotron effective mass, electron mobility and phase shift of Shubnikov-de Haas oscillations. J Phys Condens Matter 2019; 31:115701. [PMID: 30625443 DOI: 10.1088/1361-648x/aafcf4] [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] [Indexed: 06/09/2023]
Abstract
In this paper, the authors report the results of an experimental study of effective mass, electron mobility and phase shift of Shubnikov-de Haas oscillations of transverse magnetoresistance in an extended electron concentration region from 8.8 × 1015 cm-3 to 4.3 × 1018 cm-3 in single crystals of mercury selenide. The revealed features indicate that Weyl semimetal phase may exist in HgSe at low electron density. The most significant result is the discovery of an abrupt change of Berry phase [Formula: see text] at electron concentration [Formula: see text] 2 × 1018 cm-3, which we explain in terms of a manifestation of topological Lifshitz transition in HgSe that occurs by tuning Fermi energy via doping.
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Affiliation(s)
- S B Bobin
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620108 Yekaterinburg, Russia
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25
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Yang P, Wang W, Zhang X, Wang K, He L, Liu W, Xu Y. Quantum Oscillations from Nontrivial States in Quasi-Two-Dimensional Dirac Semimetal ZrTe 5 Nanowires. Sci Rep 2019; 9:3558. [PMID: 30837508 PMCID: PMC6401147 DOI: 10.1038/s41598-019-39144-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 01/16/2019] [Indexed: 11/09/2022] Open
Abstract
Recently discovered Dirac semimetal ZrTe5 bulk crystal, exhibits nontrivial conducting states in each individual layer, holding great potential for novel spintronic applications. Here, to reveal the transport properties of ZrTe5, we fabricated ZrTe5 nanowires (NWs) devices, with much larger surface-to-volume ratio than bulk materials. Quantum oscillations induced by the two-dimensional (2D) nontrivial conducting states have been observed from these NWs and a finite Berry phase of ~π is obtained by the analysis of Landau-level fan diagram. More importantly, the absence of the Aharonov-Bohm (A-B) oscillations, along with the SdH oscillations, suggests that the electrons only conduct inside each layer. And the intralayer conducting is suppressed because of the weak connection between adjacent layers. Our results demonstrate that ZrTe5 NWs can serve as a suitable quasi-2D Dirac semimetal with high mobility (~85000 cm2V-1s-1) and large nontrivial conductance contribution (up to 8.68%).
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Affiliation(s)
- Pei Yang
- Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Wei Wang
- Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Xiaoqian Zhang
- Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Kejie Wang
- Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China
| | - Liang He
- Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China.
| | - Wenqing Liu
- York Nanjing Joint Centre for Spintronics and Nanotechnology, Departments of Electronics, The University of York, York, YO10 5DD, UK
| | - Yongbing Xu
- Jiangsu Provincial Key Laboratory for Nanotechnology, Collaborative Innovation Center of Advanced Microstructures, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China.
- York Nanjing Joint Centre for Spintronics and Nanotechnology, Departments of Electronics, The University of York, York, YO10 5DD, UK.
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26
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Cho S, Park JH, Hong J, Jung J, Kim BS, Han G, Kyung W, Kim Y, Mo SK, Denlinger JD, Shim JH, Han JH, Kim C, Park SR. Experimental Observation of Hidden Berry Curvature in Inversion-Symmetric Bulk 2H-WSe_{2}. Phys Rev Lett 2018; 121:186401. [PMID: 30444409 DOI: 10.1103/physrevlett.121.186401] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 08/24/2018] [Indexed: 06/09/2023]
Abstract
We investigate the hidden Berry curvature in bulk 2H-WSe_{2} by utilizing the surface sensitivity of angle resolved photoemission (ARPES). The symmetry in the electronic structure of transition metal dichalcogenides is used to uniquely determine the local orbital angular momentum (OAM) contribution to the circular dichroism (CD) in ARPES. The extracted CD signals for the K and K^{'} valleys are almost identical, but their signs, which should be determined by the valley index, are opposite. In addition, the sign is found to be the same for the two spin-split bands, indicating that it is independent of spin state. These observed CD behaviors are what are expected from Berry curvature of a monolayer of WSe_{2}. In order to see if CD-ARPES is indeed representative of hidden Berry curvature within a layer, we use tight binding analysis as well as density functional calculation to calculate the Berry curvature and local OAM of a monolayer WSe_{2}. We find that measured CD-ARPES is approximately proportional to the calculated Berry curvature as well as local OAM, further supporting our interpretation.
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Affiliation(s)
- Soohyun Cho
- Institute of Physics and Applied Physics, Yonsei University, Seoul 03722, Korea
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Jin-Hong Park
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
| | - Jisook Hong
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Jongkeun Jung
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Beom Seo Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Garam Han
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Wonshik Kyung
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
- Advanced Light Source, Lawrence Berkeley National Laboratory, California 94720, USA
| | - Yeongkwan Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Republic of Korea
| | - S-K Mo
- Advanced Light Source, Lawrence Berkeley National Laboratory, California 94720, USA
| | - J D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, California 94720, USA
| | - Ji Hoon Shim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Department of Physics and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Jung Hoon Han
- Department of Physics, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University (SNU), Seoul 08826, Republic of Korea
| | - Seung Ryong Park
- Department of Physics, Incheon National University, Incheon 22012, Republic of Korea
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27
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Zhu H, Xiao C, Xie Y. Design of Highly Efficient Thermoelectric Materials: Tailoring Reciprocal-Space Properties by Real-Space Modification. Adv Mater 2018; 30:e1802000. [PMID: 30260549 DOI: 10.1002/adma.201802000] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/05/2018] [Indexed: 06/08/2023]
Abstract
Although restricted by the poor performance at present, thermoelectric materials for power-generation devices and solid-state Peltier coolers still possess unlimited vitality, thus capturing considerable attention. Understanding and manipulating the electrical and thermal transport mechanisms in thermoelectrics play significant roles in tailoring the properties of various thermoelectric materials. The transport behavior of electrons and phonons are closely related to the chemical composition and structure, which are defined in real space. Meanwhile, transport properties are also contingent on the band structure and phonon spectrum, both of which are represented in the reciprocal-space first Brillouin zone. Real space and reciprocal space are bridged by the Fourier transform, and the combination of real-space and reciprocal-space properties will provide more possibilities for regulating transport characteristics. Herein, a compendious discussion of the internal connection between real space and reciprocal space, and the underlying physics and chemistry is presented. Then, how the relationship between real and reciprocal space provides additional insights to govern electrical and thermal transport parameters is elaborated upon, thereby enabling the discovery and optimization of thermoelectric materials. In conclusion, specific challenges and feasible directions are discussed.
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Affiliation(s)
- Hao Zhu
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Chong Xiao
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
| | - Yi Xie
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China
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28
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Li X, Sun J, Shahi P, Gao M, MacDonald AH, Uwatoko Y, Xiang T, Goodenough JB, Cheng J, Zhou J. Pressure-induced phase transitions and superconductivity in a black phosphorus single crystal. Proc Natl Acad Sci U S A 2018; 115:9935-9940. [PMID: 30217890 PMCID: PMC6176577 DOI: 10.1073/pnas.1810726115] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [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
We report a thorough study of the transport properties of the normal and superconducting states of black phosphorus (BP) under magnetic field and high pressure with a large-volume apparatus that provides hydrostatic pressure to induce transitions from the layered A17 phase to the layered A7 phase and to the cubic phase of BP. Quantum oscillations can be observed at P ≥ 1 GPa in both resistivity and Hall voltage, and their evolutions with pressure in the A17 phase imply a continuous enlargement of Fermi surface. A significantly large magnetoresistance (MR) at low temperatures is observed in the A7 phase that becomes superconducting below a superconducting transition temperature Tc ∼ 6-13 K. Tc increases continuously with pressure on crossing the A7 to the cubic phase boundary. The strong MR effect can be fit by a modified Kohler's rule. A correlation between Tc and fitting parameters suggests that phonon-mediated interactions play dominant roles in driving the Cooper pairing, which is further supported by our density functional theory (DFT) calculations. The change of effective carrier mobility in the A17 phase under pressure derived from the MR effect is consistent with that obtained from the temperature dependence of the quantum oscillations. In situ single-crystal diffraction under high pressure indicates a total structural reconstruction instead of simple stretching of the A17 phase layers in the A17-to-A7-phase transition. This finding helps us to interpret transport properties on crossing the phase transition under high pressure.
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Affiliation(s)
- Xiang Li
- Materials Science and Engineering Program, The University of Texas at Austin, Austin, TX 78712
| | - Jianping Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Prashant Shahi
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
- Department of Physics, Deen Dayal Upadhyaya Gorakhpur University, Gorakhpur 273009, India
| | - Miao Gao
- Department of Microelectronics Science and Engineering, Faculty of Sciences, Ningbo University, Zhejiang 315211, China
| | - Allan H MacDonald
- Department of Physics, The University of Texas at Austin, Austin, TX 78712
| | - Yoshiya Uwatoko
- Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Tao Xiang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, China
| | - John B Goodenough
- Materials Science and Engineering Program, The University of Texas at Austin, Austin, TX 78712;
| | - Jinguang Cheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
- School of Physics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jianshi Zhou
- Materials Science and Engineering Program, The University of Texas at Austin, Austin, TX 78712;
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29
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Wang H, Ma L, Wang J. Tip-induced or enhanced superconductivity: a way to detect topological superconductivity. Sci Bull (Beijing) 2018; 63:1141-1158. [PMID: 36658994 DOI: 10.1016/j.scib.2018.07.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [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: 06/20/2018] [Revised: 07/23/2018] [Accepted: 07/24/2018] [Indexed: 01/21/2023]
Abstract
Topological materials, hosting topological nontrivial electronic band, have attracted widespread attentions. As an application of topology in physics, the discovery and study of topological materials not only enrich the existing theoretical framework of physics, but also provide fertile ground for investigations on low energy excitations, such as Weyl fermions and Majorana fermions, which have not been observed yet as fundamental particles. These quasiparticles with exotic physical properties make topological materials the cutting edge of scientific research and a new favorite of high tech. As a typical example, Majorana fermions, predicted to exist in the edge state of topological superconductors, are proposed to implement topological error-tolerant quantum computers. Thus, the detection of topological superconductivity has become a frontier in condensed matter physics and materials science. Here, we review a way to detect topological superconductivity triggered by the hard point contact: tip-induced superconductivity (TISC) and tip-enhanced superconductivity (TESC). The TISC refers to the superconductivity induced by a non-superconducting tip at the point contact on non-superconducting materials. We take the elaboration of the chief experimental achievement of TISC in topological Dirac semimetal Cd3As2 and Weyl semimetal TaAs as key components of this article for detecting topological superconductivity. Moreover, we also briefly introduce the main results of another exotic effect, TESC, in superconducting Au2Pb and Sr2RuO4 single crystals, which are respectively proposed as the candidates of helical topological superconductor and chiral topological superconductor. Related results and the potential mechanism are conducive to improving the comprehension of how to induce and enhance the topological superconductivity.
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Affiliation(s)
- He Wang
- Tianjin International Center for Nano Particles and Nano Systems, Tianjin University, Tianjin 300072, China; International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Lei Ma
- Tianjin International Center for Nano Particles and Nano Systems, Tianjin University, Tianjin 300072, China.
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China; State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
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30
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Abstract
One of the characteristics of topological materials is their nontrivial Berry phase. Experimental determination of this phase largely relies on a phase analysis of quantum oscillations. We study the angular dependence of the oscillations in a Dirac material [Formula: see text] and observe a striking spin-zero effect (i.e., vanishing oscillations accompanied with a phase inversion). This indicates that the Berry phase in [Formula: see text] remains nontrivial for arbitrary field direction, in contrast with previous reports. The Zeeman splitting is found to be proportional to the magnetic field based on the condition for the spin-zero effect in a Dirac band. Moreover, it is suggested that the Dirac band in [Formula: see text] is likely transformed into a line node other than Weyl points for the field directions at which the spin zero occurs. The results underline a largely overlooked spin factor when determining the Berry phase from quantum oscillations.
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31
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Gao W, Zhu X, Zheng F, Wu M, Zhang J, Xi C, Zhang P, Zhang Y, Hao N, Ning W, Tian M. A possible candidate for triply degenerate point fermions in trigonal layered PtBi 2. Nat Commun 2018; 9:3249. [PMID: 30108216 PMCID: PMC6092399 DOI: 10.1038/s41467-018-05730-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [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: 12/05/2017] [Accepted: 07/13/2018] [Indexed: 11/16/2022] Open
Abstract
Triply degenerate point (TP) fermions in tungsten–carbide-type materials (e.g., MoP), which represent new topological states of quantum matter, have generated immense interest recently. However, the TPs in these materials are found to be far below the Fermi level, leading to the TP fermions having less contribution to low-energy quasiparticle excitations. Here, we theoretically predict the existence of TP fermions with TP points close to the Fermi level in trigonal layered PtBi2 by ab initio calculations, and experimentally verify the predicted band topology by magnetotransport measurements under high magnetic fields up to 40 T. Analyses of both the pronounced Shubnikov–de Haas and de Haas–van Alphen oscillations reveal the existence of six principal Fermi pockets. Our experimental results, together with those from ab initio calculations, reveal the interplay between transport behaviors and unique electronic structures, and support the existence of TP fermions in trigonal layered PtBi2. Triply degenerate point (TP) fermions have been reported in MoP but the TPs are far below the Fermi level. Here, Guo et al. predict and verify the possible existence of TP fermions in trigonal layered PtBi2, where the TP points are close to the Fermi level.
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Affiliation(s)
- Wenshuai Gao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China.,Department of physics, University of Science and Technology of China, Hefei, 230026, China.,Institute of Physical Science and Information Technology, School of Physics and Materials Science, Anhui University, Hefei, 230601, China
| | - Xiangde Zhu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Fawei Zheng
- Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China
| | - Min Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China.,Department of physics, University of Science and Technology of China, Hefei, 230026, China
| | - Jinglei Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Chuanying Xi
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics, Beijing, 100088, China.,Beijing Computational Science Research Center, Beijing, 100193, China
| | - Yuheng Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Ning Hao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - Wei Ning
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China.
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, 230031, China. .,Institute of Physical Science and Information Technology, School of Physics and Materials Science, Anhui University, Hefei, 230601, China. .,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
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32
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Abstract
In this paper, we first review fundamental aspects of magnetoresistance in multi-valley systems based on the semiclassical theory. Then we will review experimental evidence and theoretical understanding of magnetoresistance in an archetypal multi-valley system, where the electric conductivity is set by the sum of the contributions of different valleys. Bulk bismuth has three valleys with an extremely anisotropic effective mass. As a consequence the magnetoconductivity in each valley is extremely sensitive to the orientation of the magnetic field. Therefore, a rotating magnetic field plays the role of a valley valve tuning the contribution of each valley to the total conductivity. In addition to this simple semiclassical effect, other phenomena arise in the high-field limit as a consequence of an intricate Landau spectrum. In the vicinity of the quantum limit, the orientation of magnetic field significantly affects the distribution of carriers in each valley, namely, the valley polarization is induced by the magnetic field. Moreover, experiment has found that well beyond the quantum limit, one or two valleys become totally empty. This is the only case in condensed matter physics where a Fermi sea is completely dried up by a magnetic field without a metal-insulator transition. There have been two long-standing problems on bismuth near the quantum limit: the large anisotropic Zeeman splitting of holes, and the extra peaks in quantum oscillations, which cannot be assigned to any known Landau levels. These problems are solved by taking into account the interband effect due to the spin-orbit couplings for the former, and the contributions from the twinned crystal for the latter. Up to here, the whole spectrum can be interpreted within the one-particle theory. Finally, we will discuss transport and thermodynamic signatures of breaking of the valley symmetry in this system. By this term, we refer to the observed spontaneous loss of threefold symmetry at high magnetic field and low temperature. Its theoretical understanding is still missing. We will discuss possible explanations.
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Affiliation(s)
- Zengwei Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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33
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Li S, Guo Z, Fu D, Pan XC, Wang J, Ran K, Bao S, Ma Z, Cai Z, Wang R, Yu R, Sun J, Song F, Wen J. Evidence for a Dirac nodal-line semimetal in SrAs 3. Sci Bull (Beijing) 2018; 63:535-541. [PMID: 36658839 DOI: 10.1016/j.scib.2018.04.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [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: 01/09/2018] [Revised: 03/15/2018] [Accepted: 04/17/2018] [Indexed: 01/21/2023]
Abstract
Dirac nodal-line semimetals with the linear bands crossing along a line or loop, represent a new topological state of matter. Here, by carrying out magnetotransport measurements and performing first-principle calculations, we demonstrate that such a state has been realized in high-quality single crystals of SrAs3. We obtain the nontrivial π Berry phase by analysing the Shubnikov-de Haas quantum oscillations. We also observe a robust negative longitudinal magnetoresistance induced by the chiral anomaly. Accompanying first-principles calculations identifies that a single hole pocket enclosing the loop nodes is responsible for these observations.
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Affiliation(s)
- Shichao Li
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Zhaopeng Guo
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Dongzhi Fu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Xing-Chen Pan
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Jinghui Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Kejing Ran
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Song Bao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Zhen Ma
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Zhengwei Cai
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Rui Wang
- Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Rui Yu
- School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jian Sun
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
| | - Jinsheng Wen
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
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34
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Zhang C, Lu HZ, Shen SQ, Chen YP, Xiu F. Towards the manipulation of topological states of matter: a perspective from electron transport. Sci Bull (Beijing) 2018; 63:580-594. [PMID: 36658845 DOI: 10.1016/j.scib.2018.04.007] [Citation(s) in RCA: 14] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 01/21/2023]
Abstract
The introduction of topological invariants, ranging from insulators to metals, has provided new insights into the traditional classification of electronic states in condensed matter physics. A sudden change in the topological invariant at the boundary of a topological nontrivial system leads to the formation of exotic surface states that are dramatically different from its bulk. In recent years, significant advancements in the exploration of the physical properties of these topological systems and regarding device research related to spintronics and quantum computation have been made. Here, we review the progress of the characterization and manipulation of topological phases from the electron transport perspective and also the intriguing chiral/Majorana states that stem from them. We then discuss the future directions of research into these topological states and their potential applications.
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Affiliation(s)
- Cheng Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Hai-Zhou Lu
- Institute for Quantum Science and Engineering and Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China; Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - Shun-Qing Shen
- Department of Physics, The University of Hong Kong, Hong Kong, China
| | - Yong P Chen
- Department of Physics and Astronomy, Purdue University, West Lafayette 47907, USA; Birck Nanotechnology Center, Purdue University, West Lafayette 47907, USA; School of Electrical and Computer Engineering, Purdue University, West Lafayette 47907, USA
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China; Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China.
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35
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Veit MJ, Arras R, Ramshaw BJ, Pentcheva R, Suzuki Y. Nonzero Berry phase in quantum oscillations from giant Rashba-type spin splitting in LaTiO 3/SrTiO 3 heterostructures. Nat Commun 2018; 9:1458. [PMID: 29654231 PMCID: PMC5899139 DOI: 10.1038/s41467-018-04014-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [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: 01/17/2017] [Accepted: 03/26/2018] [Indexed: 11/17/2022] Open
Abstract
The manipulation of the spin degrees of freedom in a solid has been of fundamental and technological interest recently for developing high-speed, low-power computational devices. There has been much work focused on developing highly spin-polarized materials and understanding their behavior when incorporated into so-called spintronic devices. These devices usually require spin splitting with magnetic fields. However, there is another promising strategy to achieve spin splitting using spatial symmetry breaking without the use of a magnetic field, known as Rashba-type splitting. Here we report evidence for a giant Rashba-type splitting at the interface of LaTiO3 and SrTiO3. Analysis of the magnetotransport reveals anisotropic magnetoresistance, weak anti-localization and quantum oscillation behavior consistent with a large Rashba-type splitting. It is surprising to find a large Rashba-type splitting in 3d transition metal oxide-based systems such as the LaTiO3/SrTiO3 interface, but it is promising for the development of a new kind of oxide-based spintronics. Rashba-type splitting is an effective way to manipulate the spin degrees of freedom in a solid without external magnetic field. Here, the authors demonstrate a strong Rashba-type splitting at the interface of LaTiO3 and SrTiO3 which is promising for the development of oxide-based spintronics.
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Affiliation(s)
- M J Veit
- Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
| | - R Arras
- CEMES, University of Toulouse, CNRS, UPS, 29, rue Jeanne Marvig, 31055, Toulouse, France
| | - B J Ramshaw
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.,Laboratory for Atomic and Solid State Physics, Cornell University, Ithaca, NY, 14853, USA
| | - R Pentcheva
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstrasse 1, 47057, Duisburg, Germany
| | - Y Suzuki
- Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
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36
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Li C, Wang CM, Wan B, Wan X, Lu HZ, Xie XC. Rules for Phase Shifts of Quantum Oscillations in Topological Nodal-Line Semimetals. Phys Rev Lett 2018; 120:146602. [PMID: 29694159 DOI: 10.1103/physrevlett.120.146602] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/01/2018] [Indexed: 05/12/2023]
Abstract
Nodal-line semimetals are topological semimetals in which band touchings form nodal lines or rings. Around a loop that encloses a nodal line, an electron can accumulate a nontrivial π Berry phase, so the phase shift in the Shubnikov-de Haas (SdH) oscillation may give a transport signature for the nodal-line semimetals. However, different experiments have reported contradictory phase shifts, in particular, in the WHM nodal-line semimetals (W=Zr/Hf, H=Si/Ge, M=S/Se/Te). For a generic model of nodal-line semimetals, we present a systematic calculation for the SdH oscillation of resistivity under a magnetic field normal to the nodal-line plane. From the analytical result of the resistivity, we extract general rules to determine the phase shifts for arbitrary cases and apply them to ZrSiS and Cu_{3}PdN systems. Depending on the magnetic field directions, carrier types, and cross sections of the Fermi surface, the phase shift shows rich results, quite different from those for normal electrons and Weyl fermions. Our results may help explore transport signatures of topological nodal-line semimetals and can be generalized to other topological phases of matter.
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Affiliation(s)
- Cequn Li
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - C M Wang
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
- School of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000, China
| | - Bo Wan
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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37
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Wang W, Zhang X, Xu H, Zhao Y, Zou W, He L, Xu Y. Evidence for Layered Quantized Transport in Dirac Semimetal ZrTe 5. Sci Rep 2018; 8:5125. [PMID: 29572493 DOI: 10.1038/s41598-018-23011-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 02/22/2018] [Indexed: 12/04/2022] Open
Abstract
ZrTe5 is an important semiconductor thermoelectric material and a candidate topological insulator. Here we report the observation of Shubnikov-de Hass (SdH) oscillations accompanied by quantized Hall resistance in bulk ZrTe5 crystal, with a mobility of 41,000 cm2V−1s−1. We have found that the quantum oscillations does not originate from the surface states, but from the bulk states. Each single layer ZrTe5 acted like an independent 2D electron system in the quantum Hall regime having the same carrier density and mobilities, while the bulk of the sample exhibits a multilayered quantum Hall effect.
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38
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VanGennep D, Jackson DE, Graf D, Berger H, Hamlin JJ. Evolution of the Fermi surface of BiTeCl with pressure. J Phys Condens Matter 2017; 29:295702. [PMID: 28513467 DOI: 10.1088/1361-648x/aa73b7] [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] [Indexed: 06/07/2023]
Abstract
We report measurements of Shubnikov-de Haas oscillations in the giant Rashba semiconductor BiTeCl under applied pressures up to ∼2.5 GPa. We observe two distinct oscillation frequencies, corresponding to the Rashba-split inner and outer Fermi surfaces. BiTeCl has a conduction band bottom that is split into two sub-bands due to the strong Rashba coupling, resulting in two spin-polarized conduction bands as well as a Dirac point. Our results suggest that the chemical potential lies above this Dirac point, giving rise to two Fermi surfaces. We use a simple two-band model to understand the pressure dependence of our sample parameters. Comparing our results on BiTeCl to previous results on BiTeI, we observe similar trends in both the chemical potential and the Rashba splitting with pressure.
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Affiliation(s)
- D VanGennep
- Department of Physics, University of Florida, Gainesville, FL 32611, United States of America
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Abstract
Novel topological state of matter is one of the rapidly growing fields in condensed matter physics research in recent times. While these materials are fascinating from the aspect of fundamental physics of relativistic particles, their exotic transport properties are equally compelling due to the potential technological applications. Extreme magnetoresistance and ultrahigh carrier mobility are two such major hallmarks of topological materials and often used as primary criteria for identifying new compounds belonging to this class. Recently, LaBi has emerged as a new system, which exhibits the above mentioned properties. However, the topological nature of its band structure remains unresolved. Here, using the magnetotransport and magnetization measurements, we have probed the bulk and surface states of LaBi. Similar to earlier reports, extremely large magnetoresistance and high carrier mobility have been observed with compensated electron and hole density. The Fermi surface properties have been analyzed from both Shubnikov-de Haas and de Haas-van Alphen oscillation techniques. In the magnetization measurement, a prominent paramagnetic singularity has been observed, which demonstrates the non-trivial nature of the surface states in LaBi. Our study unambiguously confirms that LaBi is a three-dimensional topological insulator with possible linear dispersion in the gapped bulk band structure.
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Affiliation(s)
- Ratnadwip Singha
- Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta, 700 064, India
| | - Biswarup Satpati
- Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta, 700 064, India
| | - Prabhat Mandal
- Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta, 700 064, India.
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40
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Abstract
Bithmuth tellurohalides BiTeX (X = Cl, Br and I) are model examples of bulk Rashba semiconductors, exhibiting a giant Rashba-type spin splitting among their both valence and conduction bands. Extensive spectroscopic and transport experiments combined with the state-of-the-art first-principles calculations have revealed many unique quantum phenomena emerging from the bulk Rashba effect in these systems. The novel features such as the exotic inter- and intra-band optical transitions, enhanced magneto-optical response, divergent orbital dia-/para-magnetic susceptibility and helical spin textures with a nontrivial Berry's phase in the momentum space are among the salient discoveries, all arising from this effect. Also, it is theoretically proposed and indications have been experimentally reported that bulk Rashba semiconductors such as BiTeI have the capability of becoming a topological insulator under the application of a hydrostatic pressure. Here, we overview these studies and show that BiTeX are an ideal platform to explore the next aspects of quantum matter, which could ultimately be utilized to create spintronic devices with novel functionalities.
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Affiliation(s)
- Mohammad Saeed Bahramy
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
| | - Naoki Ogawa
- RIKEN Center for Emergent Matter Science, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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41
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Gao W, Hao N, Zheng FW, Ning W, Wu M, Zhu X, Zheng G, Zhang J, Lu J, Zhang H, Xi C, Yang J, Du H, Zhang P, Zhang Y, Tian M. Extremely Large Magnetoresistance in a Topological Semimetal Candidate Pyrite PtBi_{2}. Phys Rev Lett 2017; 118:256601. [PMID: 28696743 DOI: 10.1103/physrevlett.118.256601] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Indexed: 06/07/2023]
Abstract
While pyrite-type PtBi_{2} with a face-centered cubic structure has been predicted to be a three-dimensional (3D) Dirac semimetal, experimental study of its physical properties remains absent. Here we report the angular-dependent magnetoresistance measurements of a PtBi_{2} single crystal under high magnetic fields. We observed extremely large unsaturated magnetoresistance (XMR) up to (11.2×10^{6})% at T=1.8 K in a magnetic field of 33 T, which is comparable to the previously reported Dirac materials, such as WTe_{2}, LaSb, and NbP. The crystals exhibit an ultrahigh mobility and significant Shubnikov-de Hass quantum oscillations with a nontrivial Berry phase. The analysis of Hall resistivity indicates that the XMR can be ascribed to the nearly compensated electron and hole. Our experimental results associated with the ab initio calculations suggest that pyrite PtBi_{2} is a topological semimetal candidate that might provide a platform for exploring topological materials with XMR in noble metal alloys.
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Affiliation(s)
- Wenshuai Gao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Department of Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Ningning Hao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Fa-Wei Zheng
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China
| | - Wei Ning
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Min Wu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Department of Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Xiangde Zhu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Guolin Zheng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Department of Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Jinglei Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Jianwei Lu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Department of Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Hongwei Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Department of Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China
| | - Chuanying Xi
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Jiyong Yang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Haifeng Du
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Ping Zhang
- Institute of Applied Physics and Computational Mathematics, Beijing 100088, People's Republic of China
- Beijing Computational Science Research Center, Beijing 100193, People's Republic of China
| | - Yuheng Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Mingliang Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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42
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Abstract
Single crystals of (Cd1−xZnx)3As2 were synthesized from high-temperature solutions and characterized in terms of their structural and electrical properties. Based on the measurements of resistivity and Hall signals, we revealed a chemical-doping-controlled transition from a three-dimensional Dirac semimetal to a semiconductor with a critical point xc ~ 0.38. We observed structural transitions from a body-center tetragonal phase to a primitive tetragonal phase then back to a body-center tetragonal phase in the solid solutions as well, which are irrelevant to the topological phase transition. This continuously tunable system controlled by chemical doping provides a platform for investigating the topological quantum phase transition of three-dimensional Dirac electrons.
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Affiliation(s)
- Hong Lu
- ICQM, School of Physics, Peking University, Beijing, 100871, China
| | - Xiao Zhang
- ICQM, School of Physics, Peking University, Beijing, 100871, China
| | - Yi Bian
- ICQM, School of Physics, Peking University, Beijing, 100871, China
| | - Shuang Jia
- ICQM, School of Physics, Peking University, Beijing, 100871, China. .,Collaborative Innovation Center of Quantum Matter, Beijing, 100871, China.
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43
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Zhang JL, Guo CY, Zhu XD, Ma L, Zheng GL, Wang YQ, Pi L, Chen Y, Yuan HQ, Tian ML. Disruption of the Accidental Dirac Semimetal State in ZrTe_{5} under Hydrostatic Pressure. Phys Rev Lett 2017; 118:206601. [PMID: 28581794 DOI: 10.1103/physrevlett.118.206601] [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: 01/11/2017] [Indexed: 06/07/2023]
Abstract
We study the effect of hydrostatic pressure on the magnetotransport properties of zirconium pentatelluride. The magnitude of resistivity anomaly gets enhanced with increasing pressure, but the transition temperature T^{*} is insensitive to it up to 2.5 GPa. In the case of H∥b, the quasilinear magnetoresistance decreases drastically from 3300% (9 T) at ambient pressure to 230% (9 T) at 2.5 GPa. Besides, the change of the quantum oscillation phase from topological nontrivial to trivial is revealed around 2 GPa. Both demonstrate that the pressure breaks the accidental Dirac node in ZrTe_{5}. For H∥c, in contrast, subtle changes can be seen in the magnetoresistance and quantum oscillations. In the presence of pressure, ZrTe_{5} evolves from a highly anisotropic to a nearly isotropic electronic system, which accompanies the disruption of the accidental Dirac semimetal state. It supports the assumption that ZrTe_{5} is a semi-3D Dirac system with linear dispersion along two directions and a quadratic one along the third.
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Affiliation(s)
- J L Zhang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - C Y Guo
- Department of Physics and Center for Correlated Matter, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China
| | - X D Zhu
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - L Ma
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - G L Zheng
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Y Q Wang
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - L Pi
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
| | - Y Chen
- Department of Physics and Center for Correlated Matter, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China
| | - H Q Yuan
- Department of Physics and Center for Correlated Matter, Zhejiang University, Hangzhou 310027, Zhejiang, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - M L Tian
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory of the Chinese Academy of Sciences, Hefei 230031, Anhui, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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44
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Wang H, Wang H, Chen Y, Luo J, Yuan Z, Liu J, Wang Y, Jia S, Liu XJ, Wei J, Wang J. Discovery of tip induced unconventional superconductivity on Weyl semimetal. Sci Bull (Beijing) 2017; 62:425-430. [PMID: 36659286 DOI: 10.1016/j.scib.2017.02.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [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: 02/20/2017] [Revised: 02/21/2017] [Accepted: 02/21/2017] [Indexed: 01/21/2023]
Abstract
Weyl fermion is a massless Dirac fermion with definite chirality, which has been long pursued since 1929. Though it has not been observed as a fundamental particle in nature, Weyl fermion can be realized as low-energy excitation around Weyl point in Weyl semimetal, which possesses Weyl fermion cones in the bulk and nontrivial Fermi arc states on the surface. As a firstly discovered Weyl semimetal, TaAs crystal possesses 12 pairs of Weyl points in the momentum space, which are topologically protected against small perturbations. Here, we report for the first time the tip induced superconductivity on TaAs crystal by point contact spectroscopy. The zero bias conductance peak as well as a conductance plateau with double conductance peaks and sharp double dips are observed in the point contact spectra simultaneously, indicating unconventional superconductivity. Our further theoretical study suggests that the induced superconductivity may have nontrivial topology. The present work opens a new route in investigating the novel superconducting states based on Weyl materials.
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Affiliation(s)
- He Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Huichao Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Yuqin Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Jiawei Luo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Zhujun Yuan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Jun Liu
- Center of Electron Microscopy, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Yong Wang
- Center of Electron Microscopy, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Xiong-Jun Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China.
| | - Jian Wei
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China.
| | - Jian Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing, China.
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Singha R, Pariari AK, Satpati B, Mandal P. Large nonsaturating magnetoresistance and signature of nondegenerate Dirac nodes in ZrSiS. Proc Natl Acad Sci U S A 2017; 114:2468-73. [PMID: 28223488 DOI: 10.1073/pnas.1618004114] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Whereas the discovery of Dirac- and Weyl-type excitations in electronic systems is a major breakthrough in recent condensed matter physics, finding appropriate materials for fundamental physics and technological applications is an experimental challenge. In all of the reported materials, linear dispersion survives only up to a few hundred millielectronvolts from the Dirac or Weyl nodes. On the other hand, real materials are subject to uncontrolled doping during preparation and thermal effect near room temperature can hinder the rich physics. In ZrSiS, angle-resolved photoemission spectroscopy measurements have shown an unusually robust linear dispersion (up to [Formula: see text]2 eV) with multiple nondegenerate Dirac nodes. In this context, we present the magnetotransport study on ZrSiS crystal, which represents a large family of materials (WHM with W = Zr, Hf; H = Si, Ge, Sn; M = O, S, Se, Te) with identical band topology. Along with extremely large and nonsaturating magnetoresistance (MR), [Formula: see text]1.4 [Formula: see text] 105% at 2 K and 9 T, it shows strong anisotropy, depending on the direction of the magnetic field. Quantum oscillation and Hall effect measurements have revealed large hole and small electron Fermi pockets. A nontrivial [Formula: see text] Berry phase confirms the Dirac fermionic nature for both types of charge carriers. The long-sought relativistic phenomenon of massless Dirac fermions, known as the Adler-Bell-Jackiw chiral anomaly, has also been observed.
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Aggarwal L, Gayen S, Das S, Kumar R, Süß V, Felser C, Shekhar C, Sheet G. Mesoscopic superconductivity and high spin polarization coexisting at metallic point contacts on Weyl semimetal TaAs. Nat Commun 2017; 8:13974. [PMID: 28071685 DOI: 10.1038/ncomms13974] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/17/2016] [Indexed: 11/11/2022] Open
Abstract
A Weyl semimetal is a topologically non-trivial phase of matter that hosts mass-less Weyl fermions, the particles that remained elusive for more than 80 years since their theoretical discovery. The Weyl semimetals exhibit unique transport properties and remarkably high surface spin polarization. Here we show that a mesoscopic superconducting phase with critical temperature Tc=7 K can be realized by forming metallic point contacts with silver (Ag) on single crystals of TaAs, while neither Ag nor TaAs are superconductors. Andreev reflection spectroscopy of such point contacts reveals a superconducting gap of 1.2 meV that coexists with a high transport spin polarization of 60% indicating a highly spin-polarized supercurrent flowing through the point contacts on TaAs. Therefore, apart from the discovery of a novel mesoscopic superconducting phase, our results also show that the point contacts on Weyl semimetals are potentially important for applications in spintronics. Topological states of matter with unique transport properties hold the potential to realize unexpected phenomena. Here, Aggarwal et al. report the coexistence of a superconducting phase and a high transport spin polarization at metallic point contacts on Weyl semimetal TaAs.
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Pariari A, Mandal P. Coexistence of topological Dirac fermions on the surface and three-dimensional Dirac cone state in the bulk of ZrTe 5 single crystal. Sci Rep 2017; 7:40327. [PMID: 28067306 PMCID: PMC5220326 DOI: 10.1038/srep40327] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 12/02/2016] [Indexed: 11/08/2022] Open
Abstract
Although, the long-standing debate on the resistivity anomaly in ZrTe5 somewhat comes to an end, the exact topological nature of the electronic band structure remains elusive till today. Theoretical calculations predicted that bulk ZrTe5 to be either a weak or a strong three-dimensional (3D) topological insulator. However, the angle resolved photoemission spectroscopy and transport measurements clearly demonstrate 3D Dirac cone state with a small mass gap between the valence band and conduction band in the bulk. From the magnetization and magneto-transport measurements on ZrTe5 single crystal, we have detected both the signature of helical spin texture from topological surface state and chiral anomaly associated with the 3D Dirac cone state in the bulk. This implies that ZrTe5 hosts a novel electronic phase of material, having massless Dirac fermionic excitation in its bulk gap state, unlike earlier reported 3D topological insulators. Apart from the band topology, it is also apparent from the resistivity and Hall measurements that the anomalous peak in the resistivity can be shifted to a much lower temperature (T < 2 K) by controlling impurity and defects.
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Affiliation(s)
- Arnab Pariari
- Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta 700 064, India
| | - Prabhat Mandal
- Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Calcutta 700 064, India
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Ali MN, Schoop LM, Garg C, Lippmann JM, Lara E, Lotsch B, Parkin SSP. Butterfly magnetoresistance, quasi-2D Dirac Fermi surface and topological phase transition in ZrSiS. Sci Adv 2016; 2:e1601742. [PMID: 28028541 PMCID: PMC5161428 DOI: 10.1126/sciadv.1601742] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/15/2016] [Indexed: 05/14/2023]
Abstract
Magnetoresistance (MR), the change of a material's electrical resistance in response to an applied magnetic field, is a technologically important property that has been the topic of intense study for more than a quarter century. We report the observation of an unusual "butterfly"-shaped titanic angular magnetoresistance (AMR) in the nonmagnetic Dirac material, ZrSiS, which we find to be the most conducting sulfide known, with a 2-K resistivity as low as 48(4) nΩ⋅cm. The MR in ZrSiS is large and positive, reaching nearly 1.8 × 105 percent at 9 T and 2 K at a 45° angle between the applied current (I || a) and the applied field (90° is H || c). Approaching 90°, a "dip" is seen in the AMR, which, by analyzing Shubnikov de Haas oscillations at different angles, we find to coincide with a very sharp topological phase transition unlike any seen in other known Dirac/Weyl materials. We find that ZrSiS has a combination of two-dimensional (2D) and 3D Dirac pockets comprising its Fermi surface and that the combination of high-mobility carriers and multiple pockets in ZrSiS allows for large property changes to occur as a function of angle between applied fields. This makes it a promising platform to study the physics stemming from the coexistence of 2D and 3D Dirac electrons as well as opens the door to creating devices focused on switching between different parts of the Fermi surface and different topological states.
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Affiliation(s)
- Mazhar N. Ali
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
- Corresponding author.
| | - Leslie M. Schoop
- Max Planck Institute for Solid State Research, Heisenbergstasse 1, 70569 Stuttgart, Germany
| | - Chirag Garg
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Judith M. Lippmann
- Max Planck Institute for Solid State Research, Heisenbergstasse 1, 70569 Stuttgart, Germany
| | - Erik Lara
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
| | - Bettina Lotsch
- Max Planck Institute for Solid State Research, Heisenbergstasse 1, 70569 Stuttgart, Germany
- Department of Chemistry, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, 81377 München, Germany
| | - Stuart S. P. Parkin
- IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
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Estrecho E, Gao T, Brodbeck S, Kamp M, Schneider C, Höfling S, Truscott AG, Ostrovskaya EA. Visualising Berry phase and diabolical points in a quantum exciton-polariton billiard. Sci Rep 2016; 6:37653. [PMID: 27886222 DOI: 10.1038/srep37653] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/01/2016] [Indexed: 11/08/2022] Open
Abstract
Diabolical points (spectral degeneracies) can naturally occur in spectra of two-dimensional quantum systems and classical wave resonators due to simple symmetries. Geometric Berry phase is associated with these spectral degeneracies. Here, we demonstrate a diabolical point and the corresponding Berry phase in the spectrum of hybrid light-matter quasiparticles-exciton-polaritons in semiconductor microcavities. It is well known that sufficiently strong optical pumping can drive exciton-polaritons to quantum degeneracy, whereby they form a macroscopically populated quantum coherent state similar to a Bose-Einstein condensate. By pumping a microcavity with a spatially structured light beam, we create a two-dimensional quantum billiard for the exciton-polariton condensate and demonstrate a diabolical point in the spectrum of the billiard eigenstates. The fully reconfigurable geometry of the potential walls controlled by the optical pump enables a striking experimental visualization of the Berry phase associated with the diabolical point. The Berry phase is observed and measured by direct imaging of the macroscopic exciton-polariton probability densities.
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Li CH, van 't Erve OM, Rajput S, Li L, Jonker BT. Direct comparison of current-induced spin polarization in topological insulator Bi 2Se 3 and InAs Rashba states. Nat Commun 2016; 7:13518. [PMID: 27853143 DOI: 10.1038/ncomms13518] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 10/11/2016] [Indexed: 01/27/2023] Open
Abstract
Three-dimensional topological insulators (TIs) exhibit time-reversal symmetry protected, linearly dispersing Dirac surface states with spin–momentum locking. Band bending at the TI surface may also lead to coexisting trivial two-dimensional electron gas (2DEG) states with parabolic energy dispersion. A bias current is expected to generate spin polarization in both systems, although with different magnitude and sign. Here we compare spin potentiometric measurements of bias current-generated spin polarization in Bi2Se3(111) where Dirac surface states coexist with trivial 2DEG states, and in InAs(001) where only trivial 2DEG states are present. We observe spin polarization arising from spin–momentum locking in both cases, with opposite signs of the measured spin voltage. We present a model based on spin dependent electrochemical potentials to directly derive the sign expected for the Dirac surface states, and show that the dominant contribution to the current-generated spin polarization in the TI is from the Dirac surface states. Spin-polarized states arising from either Rashba splitting or topological effects are expected to produce current-induced spin polarization with different magnitude and sign. Here, Li et al. observe current-generated spin polarization in both Bi2Se3 (111) and InAs (001) films, with opposite signs of the spin voltage.
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