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Mohajerani A, Faraei Z, Jafari SA. Fast nuclear spin relaxation rates in tilted cone Weyl semimetals: redshift factors from Korringa relation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:215603. [PMID: 33588403 DOI: 10.1088/1361-648x/abe64e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Spin lattice relaxation rate is investigated for 3D tilted cone Weyl semimetals (TCWSMs). The nuclear spin relaxation rate is presented as a function of temperature and tilt parameter. We find that the relaxation rate behaves as(1-ζ2)-αwithα≈ 9 where 0 ⩽ζ< 1 is the tilt parameter. We demonstrate that such a strong enhancement forζ≲ 1 that gives rise to very fast relaxation rates, is contributed by a new hyperfine interactions arising from the tilt itself. This can be attributed to the combination of anisotropy of the Fermi surface and an additional part related to the structure of the spacetime: extracting an effective density of states (DOS)ρ̃from the Korringa relation, we show that it is related to the DOSρof the tilted cone dispersion by the 'redshift factor' asρ̃=ρ/1-ζ2. We interpret this relation as NMR manifestation of an emergent underlying spacetime structure in TCWSMs.
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Affiliation(s)
- A Mohajerani
- Department of Basic Sciences, Tarbiat Modares University (TMU), Tehran 14115-175, Iran
| | - Z Faraei
- Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran
| | - S A Jafari
- Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran
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2
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Fu C, Yao M, Chen X, Maulana LZ, Li X, Yang J, Imasato K, Zhu F, Li G, Auffermann G, Burkhardt U, Schnelle W, Zhou J, Zhu T, Zhao X, Shi M, Dressel M, Pronin AV, Snyder GJ, Felser C. Revealing the Intrinsic Electronic Structure of 3D Half-Heusler Thermoelectric Materials by Angle-Resolved Photoemission Spectroscopy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2020; 7:1902409. [PMID: 31921571 PMCID: PMC6947594 DOI: 10.1002/advs.201902409] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/02/2019] [Indexed: 05/28/2023]
Abstract
Accurate determination of the intrinsic electronic structure of thermoelectric materials is a prerequisite for utilizing an electronic band engineering strategy to improve their thermoelectric performance. Herein, with high-resolution angle-resolved photoemission spectroscopy (ARPES), the intrinsic electronic structure of the 3D half-Heusler thermoelectric material ZrNiSn is revealed. An unexpectedly large intrinsic bandgap is directly observed by ARPES and is further confirmed by electrical and optical measurements and first-principles calculations. Moreover, a large anisotropic conduction band with an anisotropic factor of 6 is identified by ARPES and attributed to be one of the most important reasons leading to the high thermoelectric performance of ZrNiSn. These successful findings rely on the grown high-quality single crystals, which have fewer Ni interstitial defects and negligible in-gap states on the electronic structure. This work demonstrates a realistic paradigm to investigate the electronic structure of 3D solid materials by using ARPES and provides new insights into the intrinsic electronic structure of the half-Heusler system benefiting further optimization of thermoelectric performance.
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Affiliation(s)
- Chenguang Fu
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
| | - Mengyu Yao
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
- Swiss Light SourcePaul Scherrer InstitutCH‐5232VilligenSwitzerland
| | - Xi Chen
- Materials Science and Engineering ProgramTexas Materials InstituteThe University of Texas at AustinAustinTX78712USA
| | | | - Xin Li
- Materials Genome InstituteShanghai University99 Shangda RoadShanghai200444China
| | - Jiong Yang
- Materials Genome InstituteShanghai University99 Shangda RoadShanghai200444China
| | - Kazuki Imasato
- Department of Materials Science and EngineeringNorthwestern UniversityEvanstonIL60208USA
| | - Fengfeng Zhu
- Jülich Center for Neutron Science JCNS at Heinz Maier‐Leibnitz Zentrum (MLZ)Forschungszentrum Jülich GmbH85747GarchingGermany
- Department of Physics and AstronomyShanghai Jiao Tong UniversityShanghai200240China
| | - Guowei Li
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
| | - Gudrun Auffermann
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
| | - Ulrich Burkhardt
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
| | - Walter Schnelle
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
| | - Jianshi Zhou
- Materials Science and Engineering ProgramTexas Materials InstituteThe University of Texas at AustinAustinTX78712USA
| | - Tiejun Zhu
- State Key Laboratory of Silicon Materials and School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China
| | - Xinbing Zhao
- State Key Laboratory of Silicon Materials and School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China
| | - Ming Shi
- Swiss Light SourcePaul Scherrer InstitutCH‐5232VilligenSwitzerland
| | - Martin Dressel
- 1. Physikalisches InstitutUniversität Stuttgart70569StuttgartGermany
| | - Artem V. Pronin
- 1. Physikalisches InstitutUniversität Stuttgart70569StuttgartGermany
| | - G. Jeffrey Snyder
- Department of Materials Science and EngineeringNorthwestern UniversityEvanstonIL60208USA
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of SolidsNöthnitzer Str. 4001187DresdenGermany
- Center for Nanoscale Systems (CNS)Faculty of Arts and SciencesHarvard UniversityCambridgeMA02138USA
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3
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Yao MY, Xu N, Wu QS, Autès G, Kumar N, Strocov VN, Plumb NC, Radovic M, Yazyev OV, Felser C, Mesot J, Shi M. Observation of Weyl Nodes in Robust Type-II Weyl Semimetal WP_{2}. PHYSICAL REVIEW LETTERS 2019; 122:176402. [PMID: 31107063 DOI: 10.1103/physrevlett.122.176402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Indexed: 06/09/2023]
Abstract
Distinct to type-I Weyl semimetals (WSMs) that host quasiparticles described by the Weyl equation, the energy dispersion of quasiparticles in type-II WSMs violates Lorentz invariance and the Weyl cones in the momentum space are tilted. Since it was proposed that type-II Weyl fermions could emerge from (W,Mo)Te_{2} and (W,Mo)P_{2} families of materials, a large number of experiments have been dedicated to unveiling the possible manifestation of type-II WSMs, e.g., surface-state Fermi arcs. However, the interpretations of the experimental results are very controversial. Here, using angle-resolved photoemission spectroscopy supported by the first-principles calculations, we probe the tilted Weyl cone bands in the bulk electronic structure of WP_{2} directly, which are at the origin of Fermi arcs at the surfaces and transport properties related to the chiral anomaly in type-II WSMs. Our results ascertain that, due to the spin-orbit coupling, the Weyl nodes originate from the splitting of fourfold degenerate band-crossing points with Chern numbers C=±2 induced by the crystal symmetries of WP_{2}, which is unique among all the discovered WSMs. Our finding also provides a guiding line to observe the chiral anomaly that could manifest in novel transport properties.
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Affiliation(s)
- M-Y Yao
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Q S Wu
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - G Autès
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - N Kumar
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - O V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - C Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
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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. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:115701. [PMID: 30625443 DOI: 10.1088/1361-648x/aafcf4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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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Jiang Y, Dun Z, Moon S, Zhou H, Koshino M, Smirnov D, Jiang Z. Landau Quantization in Coupled Weyl Points: A Case Study of Semimetal NbP. NANO LETTERS 2018; 18:7726-7731. [PMID: 30403143 DOI: 10.1021/acs.nanolett.8b03418] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Weyl semimetal (WSM) is a newly discovered quantum phase of matter that exhibits topologically protected states characterized by two separated Weyl points with linear dispersion in all directions. Here, via combining theoretical analysis and magneto-infrared spectroscopy of an archetypal Weyl semimetal, niobium phosphide, we demonstrate that the coupling between Weyl points can significantly modify the electronic structure of a WSM and provide a new twist to the protected states. These findings suggest that the coupled Weyl points should be considered as the basis for analysis of realistic WSMs.
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Affiliation(s)
- Yuxuan Jiang
- School of Physics , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
- National High Magnetic Field Laboratory , Tallahassee , Florida 32310 , United States
| | - Zhiling Dun
- School of Physics , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
- Department of Physics and Astronomy , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Seongphill Moon
- National High Magnetic Field Laboratory , Tallahassee , Florida 32310 , United States
- Department of Physics , Florida State University , Tallahassee , Florida 32306 , United States
| | - Haidong Zhou
- Department of Physics and Astronomy , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Mikito Koshino
- Department of Physics , Osaka University , Toyonaka 560-0043 , Japan
| | - Dmitry Smirnov
- National High Magnetic Field Laboratory , Tallahassee , Florida 32310 , United States
| | - Zhigang Jiang
- School of Physics , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
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Weber AP, Rüßmann P, Xu N, Muff S, Fanciulli M, Magrez A, Bugnon P, Berger H, Plumb NC, Shi M, Blügel S, Mavropoulos P, Dil JH. Spin-Resolved Electronic Response to the Phase Transition in MoTe_{2}. PHYSICAL REVIEW LETTERS 2018; 121:156401. [PMID: 30362784 DOI: 10.1103/physrevlett.121.156401] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 06/27/2018] [Indexed: 06/08/2023]
Abstract
The semimetal MoTe_{2} is studied by spin- and angle-resolved photoemission spectroscopy across the centrosymmetry-breaking structural transition temperature of the bulk. A three-dimensional spin-texture is observed in the bulk Fermi surface in the low temperature, noncentrosymmetric phase that is consistent with first-principles calculations. The spin texture and two types of surface Fermi arc are not completely suppressed above the bulk transition temperature. The lifetimes of quasiparticles forming the Fermi arcs depend on thermal history and lengthen considerably upon cooling toward the bulk structural transition. The results indicate that a new form of polar instability exists near the surface when the bulk is largely in a centrosymmetric phase.
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Affiliation(s)
- Andrew P Weber
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
- Donostia International Physics Center, 20018 Donostia, Gipuzkoa, Spain
| | - Philipp Rüßmann
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - Nan Xu
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Stefan Muff
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Mauro Fanciulli
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Arnaud Magrez
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Philippe Bugnon
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Helmuth Berger
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
| | - Nicholas C Plumb
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Ming Shi
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
| | - Stefan Blügel
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | - Phivos Mavropoulos
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
- Department of Physics, National and Kapodistrian University of Athens, 15784 Zografou, Greece
| | - J Hugo Dil
- Institute of Physics, École Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland
- Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen, Switzerland
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Shi Y, Che S, Zhou K, Ge S, Pi Z, Espiritu T, Taniguchi T, Watanabe K, Barlas Y, Lake R, Lau CN. Tunable Lifshitz Transitions and Multiband Transport in Tetralayer Graphene. PHYSICAL REVIEW LETTERS 2018; 120:096802. [PMID: 29547315 DOI: 10.1103/physrevlett.120.096802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Indexed: 06/08/2023]
Abstract
As the Fermi level and band structure of two-dimensional materials are readily tunable, they constitute an ideal platform for exploring the Lifshitz transition, a change in the topology of a material's Fermi surface. Using tetralayer graphene that host two intersecting massive Dirac bands, we demonstrate multiple Lifshitz transitions and multiband transport, which manifest as a nonmonotonic dependence of conductivity on the charge density n and out-of-plane electric field D, anomalous quantum Hall sequences and Landau level crossings that evolve with n, D, and B.
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Affiliation(s)
- Yanmeng Shi
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
| | - Shi Che
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Kuan Zhou
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
| | - Supeng Ge
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
| | - Ziqi Pi
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
| | - Timothy Espiritu
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
| | - Takashi Taniguchi
- National Institute for Material Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kenji Watanabe
- National Institute for Material Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yafis Barlas
- Department of Electrical and Computer Engineering, University of California, Riverside, Riverside, California 92521, USA
| | - Roger Lake
- Department of Electrical and Computer Engineering, University of California, Riverside, Riverside, California 92521, USA
| | - Chun Ning Lau
- Department of Physics and Astronomy, University of California, Riverside, Riverside, California 92521, USA
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
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Validity of Weyl fermion picture for transition metals monopnictides TaAs, TaP, NbAs, and NbP from ab initio studies. Sci Rep 2018; 8:3534. [PMID: 29476113 PMCID: PMC5824971 DOI: 10.1038/s41598-018-21465-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 02/02/2018] [Indexed: 11/09/2022] Open
Abstract
We investigate electronic and optical properties of the topological Weyl semimetals TaAs, TaP, NbAs and NbP crystallizing in bct geometry by means of the ab initio density functional theory with spin-orbit interaction within the independent-particle approximation. The small energetical overlap of Ta5d or Nb4d derived conduction and valence bands leads to electron and/or hole pockets near the Fermi energy at the 24 Weyl nodes. The nodes give rise to two-(three-)dimensional Dirac cones for the W1 (W2) Weyl type. The band dispersion and occupation near the Weyl nodes determine the infrared optical properties. They are dominated by interband transitions, which lead to a deviation from the expected constant values of the imaginary part of the dielectric function. The resulting polarization anisotropy is also visible in the real part of the optical conductivity, whose lineshape deviates from the expected linearity. The details of the Weyl nodes are discussed in relation to recent ARPES results for TaAs and NbP, and compared with measured optical spectra for TaAs. The spectral features of the anisotropic and tilted Weyl fermions are restricted to low excitation energies above absorption onsets due to the band occupation.
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Sankar R, Peramaiyan G, Muthuselvam IP, Xu S, Hasan MZ, Chou FC. Crystal growth and transport properties of Weyl semimetal TaAs. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:015803. [PMID: 29135472 DOI: 10.1088/1361-648x/aa9a75] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the single crystal growth and transport properties of a Weyl semimetal TaAs. Unsaturated large magnetoresistance of about 22 100% at 2 K and 9 T is observed. From the Hall measurement, carrier concentrations n = 4.608 × 1024 m-3 and p = 3.099 × 1024 m-3, and mobilities µ p = 2.502 m2 V-1 s-1 and µ n = 16.785 m2 V-1 s-1 at 2 K are extracted. The de Haas-van Alphen oscillations at 2 K and 9 T suggest the presence of a Fermi surface, and the quantum electronic parameters such as effective cyclotron mass and Dingle temperature were obtained using Lifshitz-Kosevich fitting. Temperature dependent resistivity measurements at different static magnetic fields suggest the formation of an insulating gap in the Weyl semimetal TaAs. An angle-resolved photoemission spectroscopy study reveals Fermi arc surface states with different shaped features such as a long elliptical contour around each [Formula: see text] point, a bowtie-shaped contour around each [Formula: see text] point, and a crescent-shaped feature near the midpoint of each [Formula: see text] line.
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Affiliation(s)
- Raman Sankar
- Institute of Physics, Academia Sinica, Taipei 10617, Taiwan. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
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