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Medel L, Ghosh R, Martín-Ruiz A, Mandal I. Electric, thermal, and thermoelectric magnetoconductivity for Weyl/multi-Weyl semimetals in planar Hall set-ups induced by the combined effects of topology and strain. Sci Rep 2024; 14:21390. [PMID: 39271719 PMCID: PMC11399286 DOI: 10.1038/s41598-024-68615-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Accepted: 07/25/2024] [Indexed: 09/15/2024] Open
Abstract
We continue our investigation of the response tensors in planar Hall (or planar thermal Hall) configurations where a three-dimensional Weyl/multi-Weyl semimetal is subjected to the combined influence of an electric field E (and/or temperature gradient∇ r T ) and an effective magnetic field B χ , generalizing the considerations of Phys. Rev. B 108 (2023) 155132 and Physica E 159 (2024) 115914. The electromagnetic fields are oriented at a generic angle with respect to each other, thus leading to the possibility of having collinear components, which do not arise in a Hall set-up. The net effective magnetic field B χ consists of two parts-(a) an actual/physical magnetic field B applied externally; and (b) an emergent magnetic field B 5 which quantifies the elastic deformations of the sample. B 5 is an axial pseudomagnetic field because it couples to conjugate nodal points with opposite chiralities with opposite signs. Using a semiclassical Boltzmann formalism, we derive the generic expressions for the response tensors, including the effects of the Berry curvature (BC) and the orbital magnetic moment (OMM), which arise due to a nontrivial topology of the bandstructures. We elucidate the interplay of the BC-only and the OMM-dependent parts in the longitudinal and transverse (or Hall) components of the electric, thermal, and thermoelectric response tensors. Especially, for the co-planar transverse components of the response tensors, the OMM part acts exclusively in opposition (sync) with the BC-only part for the Weyl (multi-Weyl) semimetals.
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Affiliation(s)
- Leonardo Medel
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México.
| | - Rahul Ghosh
- Department of Physics, Shiv Nadar Institution of Eminence (SNIoE), Gautam Buddha Nagar, Uttar Pradesh, 201314, India
| | - Alberto Martín-Ruiz
- Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 04510, Ciudad de México, México
| | - Ipsita Mandal
- Department of Physics, Shiv Nadar Institution of Eminence (SNIoE), Gautam Buddha Nagar, Uttar Pradesh, 201314, India
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, D-79104, Freiburg, Germany
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Bonilla DA, Muñoz E. Thermoelectric transport in Weyl semimetals under a uniform concentration of torsional dislocations. NANOSCALE ADVANCES 2024; 6:2701-2712. [PMID: 38752144 PMCID: PMC11093277 DOI: 10.1039/d4na00056k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 04/01/2024] [Indexed: 05/18/2024]
Abstract
In this article, we present an effective continuum model for a Weyl semimetal, to calculate its thermal and thermoelectric transport coefficients in the presence of a uniform concentration of torsional dislocations. We model each dislocation as a cylindrical region of finite radius a, where the corresponding elastic strain is described as a gauge field leading to a local pseudo-magnetic field. The transport coefficients are obtained by a combination of scattering theory, Green's functions and the Kubo formulae in the linear response regime. We applied our theoretical results to predict the electrical and thermal conductivities as well as the Seebeck coefficient for several transition metal monopnictides, i.e. TaAs, TaP, NbAs and NbP.
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Affiliation(s)
- Daniel A Bonilla
- Facultad de Física, Pontificia Universidad Católica de Chile Vicuña Mackenna 4860 Santiago Chile
| | - Enrique Muñoz
- Facultad de Física, Pontificia Universidad Católica de Chile Vicuña Mackenna 4860 Santiago Chile
- Center for Nanotechnology and Advanced Materials CIEN-UC Avenida Vicuña Mackenna 4860 Santiago Chile
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3
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Ghosh R, Mandal I. Direction-dependent conductivity in planar Hall set-ups with tilted Weyl/multi-Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:275501. [PMID: 38547533 DOI: 10.1088/1361-648x/ad38fa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 03/28/2024] [Indexed: 04/09/2024]
Abstract
We compute the magnetoelectric conductivity tensors in planar Hall set-ups, which are built with tilted Weyl semimetals (WSMs) and multi-Weyl semimetals (mWSMs), considering all possible relative orientations of the electromagnetic fields (EandB) and the direction of the tilt. The non-Drude part of the response arises from a nonzero Berry curvature in the vicinity of the WSM/mWSM node under consideration. Only in the presence of a nonzero tilt do we find linear-in-|B|terms in set-ups where the tilt-axis is not perpendicular to the plane spanned byEandB. The advantage of the emergence of the linear-in-|B|terms is that, unlike the various|B|2-dependent terms that can contribute to experimental observations, they have purely a topological origin, and they dominate the overall response-characteristics in the realistic parameter regimes. The important signatures of these terms are that they (1) change the periodicity of the response fromπto 2π, when we consider their dependence on the angleθbetweenEandB; and (2) lead to an overall change in sign of the conductivity depending onθ, when measured with respect to theB=0case.
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Affiliation(s)
- Rahul Ghosh
- Department of Physics, Shiv Nadar Institution of Eminence (SNIoE), Gautam Buddha Nagar, Uttar Pradesh 201314, India
| | - Ipsita Mandal
- Department of Physics, Shiv Nadar Institution of Eminence (SNIoE), Gautam Buddha Nagar, Uttar Pradesh 201314, India
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, D-79104 Freiburg, Germany
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Shin D, Rubio A, Tang P. Light-Induced Ideal Weyl Semimetal in HgTe via Nonlinear Phononics. PHYSICAL REVIEW LETTERS 2024; 132:016603. [PMID: 38242673 DOI: 10.1103/physrevlett.132.016603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 01/21/2024]
Abstract
Interactions between light and matter allow the realization of out-of-equilibrium states in quantum solids. In particular, nonlinear phononics is one of the most efficient approaches to realizing the stationary electronic state in nonequilibrium. Herein, by an extended ab initio molecular dynamics method, we identify that long-lived light-driven quasistationary geometry could stabilize the topological nature in the material family of HgTe compounds. We show that coherent excitation of the infrared-active phonon mode results in a distortion of the atomic geometry with a lifetime of several picoseconds. We show that four Weyl points are located exactly at the Fermi level in this nonequilibrium geometry, making it an ideal long-lived metastable Weyl semimetal. We propose that such a metastable topological phase can be identified by photoelectron spectroscopy of the Fermi arc surface states or ultrafast pump-probe transport measurements of the nonlinear Hall effect.
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Affiliation(s)
- Dongbin Shin
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Nano-Bio Spectroscopy Group, Departamento de Fisica de Materiales, Universidad del País Vasco, UPV/EHU-20018 San Sebastián, Spain
- Center for Computational Quantum Physics (CCQ), The Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
| | - Peizhe Tang
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- School of Materials Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
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Thenapparambil A, Dos Santos GE, Li CA, Abdelghany M, Beugeling W, Buhmann H, Gould C, Zhang SB, Trauzettel B, Molenkamp LW. Fluctuations in Planar Magnetotransport Due to Tilted Dirac Cones in Topological Materials. NANO LETTERS 2023; 23:6914-6919. [PMID: 37498076 DOI: 10.1021/acs.nanolett.3c01508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Fluctuations in planar magnetotransport are ubiquitous in topological HgTe structures, in both tensile (topological insulator) and compressively strained layers (Weyl semimetal phase). We show that the common reason for the fluctuations is the presence of tilted Dirac cones combined with the formation of charge puddles. The origin of the tilted Dirac cones is the mix of the Zeeman term due to the in-plane magnetic field and quadratic contributions to the dispersion relation. We develop a network model that mimics the transport of tilted Dirac fermions in the landscape of charge puddles. The model captures the essential features of the experimental data. It should be relevant for the interpretation of planar magnetotransport in a variety of topological and small band gap materials.
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Affiliation(s)
- Arya Thenapparambil
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
| | - Graciely Elias Dos Santos
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
| | - Chang-An Li
- Faculty for Physics and Astronomy (TP4), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Mohamed Abdelghany
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
| | - Wouter Beugeling
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
| | - Hartmut Buhmann
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
| | - Charles Gould
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
| | - Song-Bo Zhang
- Department of Physics, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Björn Trauzettel
- Faculty for Physics and Astronomy (TP4), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Laurens W Molenkamp
- Faculty for Physics and Astronomy (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden, Germany
- Institute for Topological Insulators, Am Hubland, D-97074 Würzburg, Germany
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Rosenstein B, Shapiro BY. Two step I to II type transitions in layered Weyl semi-metals and their impact on superconductivity. Sci Rep 2023; 13:8450. [PMID: 37231114 DOI: 10.1038/s41598-023-35704-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 05/22/2023] [Indexed: 05/27/2023] Open
Abstract
Novel "quasi two dimensional" typically layered (semi) metals offer a unique opportunity to control the density and even the topology of the electronic matter. Along with doping and gate voltage, a robust tuning is achieved by application of the hydrostatic pressure. In Weyl semi-metals the tilt of the dispersion relation cones, [Formula: see text] increases with pressure, so that one is able to reach type II ([Formula: see text]starting from the more conventional type I Weyl semi-metals [Formula: see text]. The microscopic theory of such a transition is constructed. It is found that upon increasing pressure the I to II transition occurs in two continuous steps. In the first step the cones of opposite chirality coalesce so that the chiral symmetry is restored, while the second transition to the Fermi surface extending throughout the Brillouin zone occurs at higher pressures. Flattening of the band leads to profound changes in Coulomb screening. Superconductivity observed recently in wide range of pressure and chemical composition in Weyl semi-metals of both types. The phonon theory of pairing including the Coulomb repulsion for a layered material is constructed and applied to recent extensive experiments on [Formula: see text].
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Affiliation(s)
- Baruch Rosenstein
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, R.O.C
- Department of Physics, Institute of Superconductivity, Bar-Ilan University, 52900, Ramat Gan, Israel
| | - B Ya Shapiro
- Department of Physics, Institute of Superconductivity, Bar-Ilan University, 52900, Ramat Gan, Israel.
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Lonchakov AT, Bobin SB. Positive longitudinal magnetoconductivity induced by chiral magnetic effect in mercury selenide. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:065501. [PMID: 36379061 DOI: 10.1088/1361-648x/aca30a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/14/2022] [Indexed: 06/16/2023]
Abstract
A negative longitudinal magnetoresistance without any sign of saturation was found in a non-centrosymmetric Weyl semimetal (WSM) candidate mercury selenide in an electron concentration range of 5.5 × 1015-1.7 × 1017cm-3and a temperature range of 0.33-150 K. The magnitude of the effect varies with a sample from≈10% up to≈30% in a magnetic field of 12 T atT= 150 K. Moreover, the positive contribution to magnetoconductivity has a characteristic quadratic dependence on the magnetic field, increasing with a charged center concentration atT= 150 K. The most likely explanation for the discovered longitudinal magnetoconductivity feature lies in the chiral magnetic effect, which is inherent to WSMs. The role of the Dyakonov-Perel mechanism in inter-nodal spin relaxation is discussed in regard to HgSe.
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Affiliation(s)
- Alexander T Lonchakov
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 18 S. Kovalevskaya St., Yekaterinburg 620108, Russia
| | - Semyon B Bobin
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 18 S. Kovalevskaya St., Yekaterinburg 620108, Russia
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8
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Photonic Weyl semimetals in pseudochiral metamaterials. Sci Rep 2022; 12:18847. [PMID: 36344624 PMCID: PMC9640650 DOI: 10.1038/s41598-022-23505-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022] Open
Abstract
We investigate the photonic topological phases in pseudochiral metamaterials characterized by the magnetoelectric tensors with symmetric off-diagonal chirality components. The underlying medium is considered a photonic analogue of the type-II Weyl semimetal featured with two pairs of tilted Weyl cones in the frequency-wave vector space. As the ’spin’-degenerate condition is satisfied, the photonic system consists of two hybrid modes that are completely decoupled. By introducing the pseudospin states as the basis for the hybrid modes, the photonic system is described by two subsystems in terms of the spin-orbit Hamiltonians with spin 1, which result in nonzero spin Chern numbers that determine the topological properties. Surface modes at the interface between vacuum and the pseudochiral metamaterial exist in their common gap in the wave vector space, which are analytically formulated by algebraic equations. In particular, the surface modes are tangent to both the vacuum light cone and the Weyl cones, which form two pairs of crossing surface sheets that are symmetric about the transverse axes. At the Weyl frequency, the surface modes that connect the Weyl points form four Fermi arc-like states as line segments. Topological features of the pseudochiral metamaterials are further illustrated with the robust transport of surface modes at an irregular boundary.
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Bonilla D, Muñoz E. Electronic Transport in Weyl Semimetals with a Uniform Concentration of Torsional Dislocations. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3711. [PMID: 36296901 PMCID: PMC9611412 DOI: 10.3390/nano12203711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/05/2022] [Accepted: 10/18/2022] [Indexed: 06/16/2023]
Abstract
In this article, we consider a theoretical model for a type I Weyl semimetal, under the presence of a diluted uniform concentration of torsional dislocations. By means of a mathematical analysis for partial wave scattering (phase-shift) for the T-matrix, we obtain the corresponding retarded and advanced Green's functions that include the effects of multiple scattering events with the ensemble of randomly distributed dislocations. Combining this analysis with the Kubo formalism, and including vertex corrections, we calculate the electronic conductivity as a function of temperature and concentration of dislocations. We further evaluate our analytical formulas to predict the electrical conductivity of several transition metal monopnictides, i.e., TaAs, TaP, NbAs, and NbP.
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10
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Prots Y, Krnel M, Grin Y, Svanidze E. Superconductivity in Crystallographically Disordered LaHg 6.4. Inorg Chem 2022; 61:15444-15451. [PMID: 36053961 PMCID: PMC9533302 DOI: 10.1021/acs.inorgchem.2c01987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influence of structural disorder on superconductivity is not yet fully understood. A concurrent examination of crystallographic and physical properties of LaHg6.4 reveals that this material enters a superconducting state below Tc = 2.4 K while showing crystallographic disorder in one dimension. Lanthanum mercuride, which crystallizes in a new structure type (space group Cmcm, a = 9.779(2) Å, b = 28.891(4) Å, c = 5.0012(8) Å, Z = 8), has remained out of reach for nearly 50 years. In this crystal structure, strong disorder is present in the channels that propagate along the [001] direction. By implementing a combination of cutting-edge synthesis and characterization techniques, we were able to circumvent the complexity associated with the low formation temperature and chemical reactivity of this substance and study the superconductivity of LaHg6.4 in detail.
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Affiliation(s)
- Yurii Prots
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nothnitzer Str. 40, Dresden01187, Germany
| | - Mitja Krnel
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nothnitzer Str. 40, Dresden01187, Germany
| | - Yuri Grin
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nothnitzer Str. 40, Dresden01187, Germany
| | - Eteri Svanidze
- Max-Planck-Institut für Chemische Physik fester Stoffe, Nothnitzer Str. 40, Dresden01187, Germany
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11
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Tu XH, Bo T, Liu PF, Yin W, Hao N, Wang BT. Superconductivity in Mo-P compounds under pressure and in double-Weyl semimetal Hex-MoP 2. Phys Chem Chem Phys 2022; 24:7893-7900. [PMID: 35302567 DOI: 10.1039/d1cp05685a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on first-principles calculations, we predict five global stable molybdenum phosphorus compounds in the pressure range of 0-300 GPa. All of them display superconductivity with different transition temperatures. Meanwhile, we find that a metastable crystal hex-MoP2, crystallized in a noncentrosymmetric structure, is a double-Weyl semimetal and the Weyl point is in the H-K path. The long Fermi arcs and the topological surface states, which can be observed by angle-resolved photoemission spectroscopy, emerge at the (100) surface below the Fermi level. Furthermore, we find that the superconductivity in hex-MoP2 can be enhanced by carrier doping. Due to the breaking of inversion symmetry, the unconventional spin-triplet pairing coexists with spin-singlet pairing in channel . Based on our theoretical model, there are the superconducting band gaps in both pairings. Our work provides a new platform of hex-MoP2 for studying both topological double-Weyl semimetal and superconductivity.
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Affiliation(s)
- Xin-Hai Tu
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China. .,Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, China.,University of Chinese Academy of Sciences, Beijing 100039, China
| | - Tao Bo
- Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, China.,Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences (CAS), Ningbo, Zhejiang 315201, China
| | - Peng-Fei Liu
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China. .,Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, China
| | - Wen Yin
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China. .,Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, China.,University of Chinese Academy of Sciences, Beijing 100039, China
| | - Ning Hao
- Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
| | - Bao-Tian Wang
- Institute of High Energy Physics, Chinese Academy of Sciences (CAS), Beijing 100049, China. .,Spallation Neutron Source Science Center, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803, China.,University of Chinese Academy of Sciences, Beijing 100039, China.,Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
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Anh LD, Takase K, Chiba T, Kota Y, Takiguchi K, Tanaka M. Elemental Topological Dirac Semimetal α-Sn with High Quantum Mobility. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2104645. [PMID: 34647378 DOI: 10.1002/adma.202104645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/12/2021] [Indexed: 06/13/2023]
Abstract
α-Sn provides an ideal avenue to investigate novel topological properties owing to its rich diagram of topological phases and simple elemental material structure. Thus far, however, the realization of high-quality α-Sn remains a challenge, which limits the understanding of its quantum transport properties and device applications. Here, epitaxial growth of α-Sn on InSb (001) with the highest quality thus far is presented. The studied samples exhibit unprecedentedly high quantum mobilities of both the surface state (30 000 cm2 V-1 s-1 ), which is ten times higher than the previously reported values, and the bulk heavy-hole state (1800 cm2 V-1 s-1 ), which is never obtained experimentally. These excellent features allow quantitative characterization of the nontrivial interfacial and bulk band structure of α-Sn via a thorough investigation of Shubnikov-de Haas oscillations combined with first-principles calculations. The results firmly identify that α-Sn grown on InSb (001) is a topological Dirac semimetal (TDS). Furthermore, a crossover from the TDS to a 2D topological insulator and a subsequent phase transition to a trivial insulator when varying the thickness of α-Sn are demonstrated. This work indicates that α-Sn is an excellent model system to study novel topological phases and a prominent material candidate for topological devices.
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Affiliation(s)
- Le Duc Anh
- Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- Institute of Engineering Innovation, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan
| | - Kengo Takase
- Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Takahiro Chiba
- National Institute of Technology, Fukushima College, 30 Aza-Nagao, Tairakamiarakawa, Iwaki, Fukushima, 970-8034, Japan
| | - Yohei Kota
- National Institute of Technology, Fukushima College, 30 Aza-Nagao, Tairakamiarakawa, Iwaki, Fukushima, 970-8034, Japan
| | - Kosuke Takiguchi
- Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Masaaki Tanaka
- Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
- Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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13
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Thermo-Magneto-Electric Transport through a Torsion Dislocation in a Type I Weyl Semimetal. NANOMATERIALS 2021; 11:nano11112972. [PMID: 34835736 PMCID: PMC8619483 DOI: 10.3390/nano11112972] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/29/2021] [Accepted: 11/03/2021] [Indexed: 12/02/2022]
Abstract
Herein, we study electronic and thermoelectric transport in a type I Weyl semimetal nanojunction, with a torsional dislocation defect, in the presence of an external magnetic field parallel to the dislocation axis. The defect is modeled in a cylindrical geometry, as a combination of a gauge field accounting for torsional strain and a delta-potential barrier for the lattice mismatch effect. In the Landauer formalism, we find that due to the combination of strain and magnetic field, the electric current exhibits chiral valley-polarization, and the conductance displays the signature of Landau levels. We also compute the thermal transport coefficients, where a high thermopower and a large figure of merit are predicted for the junction.
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Li R, Lv B, Tao H, Shi J, Chong Y, Zhang B, Chen H. Ideal type-II Weyl points in topological circuits. Natl Sci Rev 2021; 8:nwaa192. [PMID: 34691684 PMCID: PMC8310763 DOI: 10.1093/nsr/nwaa192] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 05/19/2020] [Accepted: 08/19/2020] [Indexed: 11/21/2022] Open
Abstract
Weyl points (WPs), nodal degenerate points in three-dimensional (3D) momentum space, are said to be 'ideal' if they are symmetry-related and well-separated, and reside at the same energy and far from nontopological bands. Although type-II WPs have unique spectral characteristics compared with type-I counterparts, ideal type-II WPs have not yet been reported because of a lack of an experimental platform with enough flexibility to produce strongly tilted dispersion bands. Here, we experimentally realize a topological circuit that hosts only topological bands with a minimal number of four ideal type-II WPs. By stacking two-dimensional (2D) layers of inductor-capacitor (LC) resonator dimers with the broken parity inversion symmetry (P), we achieve a strongly tilted band structure with two group velocities in the same direction, and topological surface states in an incomplete bandgap. Our results establish an ideal system for the further study of Weyl physics and other exotic topological phenomena.
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Affiliation(s)
- Rujiang Li
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
- ZJU-Hangzhou Global Science and Technology Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Zhejiang University, Hangzhou 310027, China
| | - Bo Lv
- Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin 150001, China
| | - Huibin Tao
- School of Software Engineering, Xi’an Jiaotong University, Xi’an 710054, China
| | - Jinhui Shi
- Key Laboratory of In-Fiber Integrated Optics of Ministry of Education, College of Physics and Optoelectronic Engineering, Harbin Engineering University, Harbin 150001, China
| | - Yidong Chong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, Nanyang Technological University, Singapore 637371, Singapore
| | - Hongsheng Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China
- ZJU-Hangzhou Global Science and Technology Innovation Center, Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Zhejiang University, Hangzhou 310027, China
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15
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Xie YM, Gao XJ, Xu XY, Zhang CP, Hu JX, Gao JZ, Law KT. Kramers nodal line metals. Nat Commun 2021; 12:3064. [PMID: 34031382 PMCID: PMC8144424 DOI: 10.1038/s41467-021-22903-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 04/06/2021] [Indexed: 11/09/2022] Open
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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16
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Shojaei IA, Pournia S, Le C, Ortiz BR, Jnawali G, Zhang FC, Wilson SD, Jackson HE, Smith LM. A Raman probe of phonons and electron-phonon interactions in the Weyl semimetal NbIrTe 4. Sci Rep 2021; 11:8155. [PMID: 33854110 PMCID: PMC8047047 DOI: 10.1038/s41598-021-87302-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/25/2021] [Indexed: 02/02/2023] Open
Abstract
There is tremendous interest in measuring the strong electron-phonon interactions seen in topological Weyl semimetals. The semimetal NbIrTe4 has been proposed to be a Type-II Weyl semimetal with 8 pairs of opposite Chirality Weyl nodes which are very close to the Fermi energy. We show using polarized angular-resolved micro-Raman scattering at two excitation energies that we can extract the phonon mode dependence of the Raman tensor elements from the shape of the scattering efficiency versus angle. This van der Waals semimetal with broken inversion symmetry and 24 atoms per unit cell has 69 possible phonon modes of which we measure 19 modes with frequencies and symmetries consistent with Density Functional Theory calculations. We show that these tensor elements vary substantially in a small energy range which reflects a strong variation of the electron-phonon coupling for these modes.
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Affiliation(s)
| | | | - Congcong Le
- Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
- Max Planck Institute for Chemical Physics of Solids, 01187, Dresden, Germany
| | - Brenden R Ortiz
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- California Nanosystems Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Giriraj Jnawali
- Department of Physics, University of Cincinnati, Cincinnati, OH, USA
| | - Fu-Chun Zhang
- Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing, 100190, China
| | - Stephen D Wilson
- Materials Department, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- California Nanosystems Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Howard E Jackson
- Department of Physics, University of Cincinnati, Cincinnati, OH, USA
| | - Leigh M Smith
- Department of Physics, University of Cincinnati, Cincinnati, OH, USA.
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17
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Chatterjee S, Khalid S, Inbar HS, Goswami A, Guo T, Chang YH, Young E, Fedorov AV, Read D, Janotti A, Palmstrøm CJ. Controlling magnetoresistance by tuning semimetallicity through dimensional confinement and heteroepitaxy. SCIENCE ADVANCES 2021; 7:7/16/eabe8971. [PMID: 33853778 PMCID: PMC8046380 DOI: 10.1126/sciadv.abe8971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Controlling electronic properties via band structure engineering is at the heart of modern semiconductor devices. Here, we extend this concept to semimetals where, using LuSb as a model system, we show that quantum confinement lifts carrier compensation and differentially affects the mobility of the electron and hole-like carriers resulting in a strong modification in its large, nonsaturating magnetoresistance behavior. Bonding mismatch at the heteroepitaxial interface of a semimetal (LuSb) and a semiconductor (GaSb) leads to the emergence of a two-dimensional, interfacial hole gas. This is accompanied by a charge transfer across the interface that provides another avenue to modify the electronic structure and magnetotransport properties in the ultrathin limit. Our work lays out a general strategy of using confined thin-film geometries and heteroepitaxial interfaces to engineer electronic structure in semimetallic systems, which allows control over their magnetoresistance behavior and simultaneously provides insights into its origin.
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Affiliation(s)
- Shouvik Chatterjee
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA.
- Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India
| | - Shoaib Khalid
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
| | - Hadass S Inbar
- Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - Aranya Goswami
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
| | - Taozhi Guo
- Department of Physics, University of California, Santa Barbara, CA 93106, USA
| | - Yu-Hao Chang
- Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - Elliot Young
- Materials Department, University of California, Santa Barbara, CA 93106, USA
| | - Alexei V Fedorov
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Dan Read
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA
- School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA, UK
| | - Anderson Janotti
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA.
| | - Chris J Palmstrøm
- Department of Electrical and Computer Engineering, University of California, Santa Barbara, CA 93106, USA.
- Materials Department, University of California, Santa Barbara, CA 93106, USA
- California NanoSystems Institute, University of California, Santa Barbara, CA 93106, USA
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18
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Jin L, Wang L, Zhang X, Liu Y, Dai X, Gao H, Liu G. Fully spin-polarized Weyl fermions and in/out-of-plane quantum anomalous Hall effects in a two-dimensional d 0 ferromagnet. NANOSCALE 2021; 13:5901-5909. [PMID: 33725053 DOI: 10.1039/d0nr07556f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The quantum anomalous Hall effect (QAHE) in intrinsic ferromagnets has attracted considerable attention recently. Previously, studies of the QAHE have mostly focused on the default assumption of out-of-plane magnetization. In fact, the QAHE can also be achieved via in-plane magnetization, but such candidate materials are very scarce. Here, we find that two-dimensional (2D) YN2 not only possesses the previously reported out-of-plane QAHE, but it also possesses a tunable in-plane QAHE. More importantly, unlike the previously reported in-plane QAHE in d/f-type ferromagnets, here we report the effect in a 2D d0 ferromagnet, namely YN2, for the first time. In the ground state, a YN2 monolayer has a half-metal band structure, and manifests six pairs of fully spin-polarized Weyl points at the Fermi level. When spin-orbit coupling is included, the YN2 monolayer can realize multiple topological phases, determined based on the magnetization direction. Under in-plane magnetization, the YN2 monolayer shows either the Weyl state or in-plane QAHE state. Remarkably, the Chern number (±1) and the propagating direction of QAHE edge channels can be continuously switched via shifting the direction of the in-plane magnetic field. When magnetization is applied out-of-plane, the YN2 monolayer realizes an out-of-plane QAHE phase with a high Chern number of 3. The nontrivial edge states for all the topological phases in the YN2 monolayer have been clearly identified. This work suggests that 2D YN2 is an excellent candidate for investigating in-plane QAHE phases in d0 ferromagnets.
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Affiliation(s)
- Lei Jin
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China.
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19
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Sattigeri RM, Gajaria TK, Jha PK, Śpiewak P, Kurzydłowski KJ. Emergence of - s, - p- dband inversion in zincblende gold iodide topological insulator and its thermoelectric properties. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:155402. [PMID: 33682681 DOI: 10.1088/1361-648x/abdce8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/18/2021] [Indexed: 06/12/2023]
Abstract
We employfirst-principlescalculations to investigate the topological states (TS) and thermoelectric (TE) transport properties of three dimensional (3D) gold iodide (AuI) which belongs to the zincblende family. We explore, semi-metal (SM) to topological conductor (TC) and topological insulator (TI) phase transitions. Under pristine conditions, AuI exhibits Dirac SM nature but, under the influence of mild isotropic compressive pressure the system undergoes electronic quantum phase transition driving it into non-trivial topological state. This state exhibits Dresselhaus like band spin splitting leading to a TC state. In order to realize TI state from the SM state, we break the cubic symmetry of the system by introducing a compressive pressure along (001) crystal direction. The non-trivial TI nature of the system is characterized by the emergence of robust surface states and theZ2invariantν0= 1 which indicates a strong TI nature. A novel facet of the phase transition discussed here is, the -sand -p, -dorbital band inversion mechanism which is unconventional as compared to previously explored TI families. This mechanism unravels new path by which TI materials can be predicted. Also, we investigated the lattice and electronic contributions to the TE transport properties. We characterize the TE performance by calculating the figure of merit (zT) and find that, at room temperature (300 K) and for a fixed doping concentration (i.e.,n= 1 × 1019 cm-3) the zT is 0.55 and 0.53 for electrons and holes respectively. This is quite remarkable since, higher values of zT are generally predicted at higher temperature scales whereas, zT values as in the present case are desired at room temperatures for various energy applications. The manifestation of non-trivial TS governed by the unconventional band inversion mechanism and the TE properties of AuI make it a unique multi-functional candidate with probable thermoelectric and spintronic applications.
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Affiliation(s)
- Raghottam M Sattigeri
- Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002, India
| | - Trupti K Gajaria
- Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002, India
| | - Prafulla K Jha
- Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara-390002, India
| | - Piotr Śpiewak
- Materials Design Division, Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Wołoska Str., 02-507 Warsaw, Poland
| | - Krzysztof J Kurzydłowski
- Materials Design Division, Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Wołoska Str., 02-507 Warsaw, Poland
- Faculty of Mechanical Engineering, Bialystok University of Technology, 45C Wiejska Str., 15-351, Bialystok, Poland
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20
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Jia T, Meng W, Zhang H, Liu C, Dai X, Zhang X, Liu G. Weyl Fermions in VI 3 Monolayer. Front Chem 2020; 8:722. [PMID: 33005602 PMCID: PMC7479203 DOI: 10.3389/fchem.2020.00722] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/14/2020] [Indexed: 11/18/2022] Open
Abstract
We report the presence of a Weyl fermion in VI3 monolayer. The material shows a sandwich-like hexagonal structure and stable phonon spectrum. It has a half-metal band structure, where only the bands in one spin channel cross the Fermi level. There are three pairs of Weyl points slightly below the Fermi level in spin-up channel. The Weyl points show a clean band structure and are characterized by clear Fermi arcs edge state. The effects of spin-orbit coupling, electron correlation, and lattice strain on the electronic band structure were investigated. We find that the half-metallicity and Weyl points are robust against these perturbations. Our work suggests VI3 monolayer is an excellent Weyl half-metal.
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Affiliation(s)
- Taoyuan Jia
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
| | - Weizhen Meng
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
| | - Haopeng Zhang
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
| | - Chunhai Liu
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
| | - Xuefang Dai
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
| | - Xiaoming Zhang
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
| | - Guodong Liu
- School of Material Sciences and Engineering, Hebei University of Technology, Tianjin, China
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21
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Yang Y, Gao Z, Feng X, Huang YX, Zhou P, Yang SA, Chong Y, Zhang B. Ideal Unconventional Weyl Point in a Chiral Photonic Metamaterial. PHYSICAL REVIEW LETTERS 2020; 125:143001. [PMID: 33064518 DOI: 10.1103/physrevlett.125.143001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
Unconventional Weyl points (WPs), carrying topological charge 2 or higher, possess interesting properties different from ordinary charge-1 WPs, including multiple Fermi arcs that stretch over a large portion of the Brillouin zone. Thus far, such WPs have been observed in chiral materials and acoustic metamaterials, but there has been no clean demonstration in photonics in which the unconventional photonic WPs are separated from trivial bands. We experimentally realize an ideal symmetry-protected photonic charge-2 WP in a three-dimensional topological chiral microwave metamaterial. We use field mapping to directly observe the projected bulk dispersion, as well as the two long surface arcs that form a noncontractible loop wrapping around the surface Brillouin zone. The surface states span a record-wide frequency window of around 22.7% relative bandwidth. We demonstrate that the surface states exhibit a novel topological self-collimation property and are robust against disorder. This work provides an ideal photonic platform for exploring fundamental physics and applications of unconventional WPs.
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Affiliation(s)
- Yihao Yang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Zhen Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Xiaolong Feng
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yue-Xin Huang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Peiheng Zhou
- National Engineering Research Center of Electromagnetic Radiation Control Materials, State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Yidong Chong
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Baile Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
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22
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Observation of Dirac state in half-Heusler material YPtBi. Sci Rep 2020; 10:12343. [PMID: 32704042 PMCID: PMC7378050 DOI: 10.1038/s41598-020-69284-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 07/09/2020] [Indexed: 12/01/2022] Open
Abstract
The prediction of non-trivial topological electronic states in half-Heusler compounds makes these materials good candidates for discovering new physics and devices as half-Heusler phases harbour a variety of electronic ground states, including superconductivity, antiferromagnetism, and heavy-fermion behaviour. Here, we report a systematic studies of electronic properties of a superconducting half-Heusler compound YPtBi, in its normal state, investigated using angle-resolved photoemission spectroscopy. Our data reveal the presence of a Dirac state at the \documentclass[12pt]{minimal}
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\begin{document}$$\Gamma$$\end{document}Γ point of the Brillouin zone at 500 meV below the Fermi level. We observe the presence of multiple Fermi surface pockets, including two concentric hexagonal and six half-oval shaped pockets at the \documentclass[12pt]{minimal}
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\begin{document}$$\Gamma$$\end{document}Γ and K points of the Brillouin zone, respectively. Furthermore, our measurements show Rashba-split bands and multiple surface states crossing the Fermi level, this is also supported by the first-principles calculations. Our findings of a Dirac state in YPtBi contribute to the establishing of half-Heusler compounds as a potential platform for novel topological phases.
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23
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Yalameha S, Nourbakhsh Z. Coexistence of type-I and critical-type nodal line states in intermetallic compounds ScM (M = Cu, Ag, Au). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:295502. [PMID: 32187591 DOI: 10.1088/1361-648x/ab80f4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In recent years, topological semimetals such as Weyl, Dirac, and nodal-line semimetals have been a hot topic in the field of condensed matter physics. Depending on the orientation of band crossing in momentum space, topological semimetals and metals can be identified as type-I or type-II. Here, we report the coexistence of two new types of topological metal phase in the ScM (M = Cu, Ag, Au) intermetallic compounds (IMCs): (1) multi-nodal-lines semimetals (above Fermi energy), (2) critical-type nodal-lines (lower than Fermi energy). The first case has already been investigated. So, in this paper, we focus on the second case. We find that these IMCs can be an existing topological metal lower than Fermi energy, which are characterized with type-I (for ScCu and ScAu) and critical-type (for ScAg) nodal-lines in the bulk and drumhead liked surface states in the absence of the spin-orbit coupling (SOC). It has also been shown that when SOC is included, these compounds are converted into topological metal materials.
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Affiliation(s)
- Shahram Yalameha
- Department of Physics, Faculty of Sciences, University of Isfahan, Isfahan, Iran
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24
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Meng W, Zhang X, He T, Jin L, Dai X, Liu Y, Liu G. Ternary compound HfCuP: An excellent Weyl semimetal with the coexistence of type-I and type-II Weyl nodes. J Adv Res 2020; 24:523-528. [PMID: 32612858 PMCID: PMC7320317 DOI: 10.1016/j.jare.2020.05.026] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/26/2020] [Accepted: 05/31/2020] [Indexed: 11/29/2022] Open
Abstract
In most Weyl semimetal (WSMs), the Weyl nodes with opposite chiralities usually have the same type of band dispersions (either type-I or type-II), whereas realistic candidate materials hosting different types of Weyl nodes have not been identified to date. Here we report for the first time that, a ternary compound HfCuP, is an excellent WSM with the coexistence of type-I and type-II Weyl nodes. Our results show that, HfCuP totally contains six pairs of type-I and six pairs of type-II Weyl nodes in the Brillouin zone, all locating at the H-K path. These Weyl nodes situate slightly below the Fermi level, and do not coexist with other extraneous bands. The nontrivial band structure in HfCuP produces clear Fermi arc surface states in the (1 0 0) surface projection. Moreover, we find the Weyl nodes in HfCuP can be effectively tuned by strain engineering. These characteristics make HfCuP a potential candidate material to investigate the novel properties of type-I and type-II Weyl fermions, as well as the potential entanglements between them.
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Affiliation(s)
- Weizhen Meng
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Xiaoming Zhang
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.,State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China
| | - Tingli He
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Lei Jin
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Xuefang Dai
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Ying Liu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Guodong Liu
- School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.,State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Hebei University of Technology, Tianjin 300130, China.,School of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400044, China
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25
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Huang X, Deng W, Li F, Lu J, Liu Z. Ideal Type-II Weyl Phase and Topological Transition in Phononic Crystals. PHYSICAL REVIEW LETTERS 2020; 124:206802. [PMID: 32501085 DOI: 10.1103/physrevlett.124.206802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Ideal Weyl points, which are related by symmetry and thus reside at the same frequency, could offer further insight into the Weyl physics. The ideal type-I Weyl points have been observed in photonic crystals, but the ideal type-II Weyl points with tilted conelike band dispersions are still not realized. Here we present the observation of the ideal type-II Weyl points of the minimal number in three-dimensional phononic crystals and, in the meantime, the topological phase transition from the Weyl semimetal to the valley insulators of two distinct types. The Fermi-arc surface states are shown to exist on the surfaces of the Weyl phase, and the Fermi-circle surface states are also observed, but on the interface of the two distinct valley phases. Intriguing wave partition of the Fermi-circle surface states is demonstrated.
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Affiliation(s)
- Xueqin Huang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Weiyin Deng
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Feng Li
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Jiuyang Lu
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Zhengyou Liu
- Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
- Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
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26
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Krishtopenko SS, Antezza M, Teppe F. Hybridization of topological surface states with a flat band. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:165501. [PMID: 31899908 DOI: 10.1088/1361-648x/ab6741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We address the problem of hybridization between topological surface states and a non-topological flat bulk band. Our model, being a mixture of three-dimensional Bernevig-Hughes-Zhang and two-dimensional pseudospin-1 Hamiltonian, allows explicit treatment of the topological surface state evolution by continuously changing the hybridization between the inverted bands and an additional 'parasitic' flat band in the bulk. We show that the hybridization with a flat band lying below the edge of the conduction band converts the initial Dirac-like surface states into a branch below and one above the flat band. Our results univocally demonstrate that the upper branch of the topological surface states is formed by Dyakonov-Khaetskii surface states, known for HgTe since the 1980s. Additionally we explore an evolution of the surface states and the arising of Fermi arcs in Dirac semimetals when the flat band crosses the conduction band.
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Affiliation(s)
- Sergey S Krishtopenko
- Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-Université de Montpellier, F-34095 Montpellier, France
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27
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Fu YL, Zhang ZJ, Li CK, Sang HB, Cheng W, Zhang FS. Electronic stopping power for slow ions in the low-hardness semimetal HgTe using first-principles calculations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:105701. [PMID: 31747646 DOI: 10.1088/1361-648x/ab598c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The electronic stopping power for low-velocity ions (including protons, [Formula: see text]-particles, and [Formula: see text]) is investigated in a novel semimetal HgTe system, where the data are obtained with the aid of Ehrenfest dynamics combined with time-dependent density functional theory. For the light projectile ions (protons and [Formula: see text]-particles), the linear and nonlinear behaviors of electronic stopping power in three different channel directions are analyzed in detail. In the case where the projectile ion is a proton, the linear results for the threshold velocity are correlated with an indirect band gap; the direction of the electronic stopping power depends on the radial drag force, the channeling electronic density and the trapped charge. More notably, we report an interesting channel-geometry fact, i.e. that the electronic stopping power of HgTe is powerfully modulated by the impact parameters. The parallel off-center tracks increase the electronic stopping power, making it more consistent with the SRIM data. In the case of an [Formula: see text]-particle as the projectile ion, nonlinear behavior that varies with velocity can be ascribed to the charge transfer, which is another mode of energy dissipation. In addition, when the slightly heavier projectile [Formula: see text] travels through the medium HgTe, the projectile [Formula: see text] can capture more free charges than the protons and [Formula: see text]-particles under the same circumstances. Especially, for the projectile in the off-channel, the electronic stopping power is close to the SRIM data with the decrease of the impact parameter. These results extend the study of radiation damage to a new field of materials.
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Affiliation(s)
- Yan-Long Fu
- The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China. Beijing Radiation Center, Beijing 100875, People's Republic of China
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28
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Meng L, Li Y, Wu J, Zhao L, Zhong J. A type of novel Weyl semimetal candidate: layered transition metal monochalcogenides Mo 2XY (X, Y = S, Se, Te, X ≠ Y). NANOSCALE 2020; 12:4602-4611. [PMID: 32043508 DOI: 10.1039/c9nr09123h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Based on ab initio calculations and the Wannier-based tight-binding method, we studied the topological electronic properties and strain modulation of transition metal monochalcogenides (TMM) Mo2XY (X, Y = S, Se, Te, X ≠ Y). These materials are nodal line semimetals in the absence of spin-orbit coupling (SOC). The presence of SOC turns them into Weyl semimetals with 24 Weyl nodes located in the kz≠ 0 planes and related by time-reversal, rotation C3z, and mirror symmetries. The maximal separation between two neighboring Weyl points with opposite chirality is of the order of magnitude of 0.10 Å-1, which can be readily accessed by angle-resolved photoemission spectroscopy (ARPES). The Weyl semimetal phase shows great robustness and demonstrates different responses under uniaxial and biaxial strain. Intriguingly, the location of the Weyl point changes significantly, resulting in a striking modulation of topological properties under in-plane biaxial strain. Our finding provides a realistic and promising platform for studying and manipulating the behavior of Weyl fermions in experiments.
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Affiliation(s)
- Lijun Meng
- School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, Hunan, People's Republic of China.
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Oktay G, Sarısaman M, Tas M. Lasing with Topological Weyl Semimetal. Sci Rep 2020; 10:3127. [PMID: 32080220 PMCID: PMC7033241 DOI: 10.1038/s41598-020-59423-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 01/21/2020] [Indexed: 11/09/2022] Open
Abstract
Lasing behavior of optically active planar topological Weyl semimetal (TWS) is investigated in view of the Kerr and Faraday rotations. Robust topological character of TWS is revealed by the presence of Weyl nodes and relevant surface conductivities. We focus our attention on the surfaces where no Fermi arcs are formed, and thus Maxwell equations contain topological terms. We explicitly demonstrate that two distinct lasing modes arise because of the presence of effective refractive indices which lead to the birefringence phenomena. Transfer matrix is constructed in such a way that reflection and transmission amplitudes involve 2 × 2 matrix-valued components describing the bimodal character of the TWS laser. We provide associated parameters of the topological laser system yielding the optimal impacts. We reveal that gain values corresponding to the lasing threshold display a quantized behavior, which occurs due to topological character of the system. Our proposal is supported by the corresponding graphical demonstrations. Our observations and predictions suggest a concrete way of forming TWS laser and coherent perfect absorber; and are awaited to be confirmed by an experimental realization based on our computations.
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Affiliation(s)
- Güneş Oktay
- Department of Physics, Istanbul University, 34134, Vezneciler, Istanbul, Turkey
| | - Mustafa Sarısaman
- Department of Physics, Istanbul University, 34134, Vezneciler, Istanbul, Turkey.
| | - Murat Tas
- Department of Physics, Gebze Technical University, 41400, Kocaeli, Turkey
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30
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Lonchakov AT, Bobin SB, Deryushkin VV, Neverov VN. Observation of quantum topological Hall effect in the Weyl semimetal candidate HgSe. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:405706. [PMID: 31216527 DOI: 10.1088/1361-648x/ab2b30] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The magnetoresistance (MR) and Hall effect of a single HgSe crystal with an extremely low electron concentration of 8.8 × 1015 cm-3 were studied in a quantising magnetic field applied both along and across the direction of the electric current. As the result, a broad plateau was discovered in the ordinary (transverse) Hall resistance in the quantum limit. Within a framework of quantum spin Hall effect for an inversion breaking Weyl semimetal, we associate this plateau with a contribution to Hall conductivity from Chern insulator edge states when only a zero Landau level is occupied. In addition to the plateau in the quantum limit, we also detected a well-developed plateau-like behaviour in a phenomenologically-introduced 'longitudinal' Hall resistivity. In the 'longitudinal' Hall conductivity, a step-like behaviour was revealed, which we identify with the discovery of half-integer quantum spin Hall effect in HgSe. This effect, being purely topological in origin, supplements the non-trivial Weyl semimetal physics and may serve as a promising magnetotransport method for the detection of Weyl nodes in a studied material.
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Affiliation(s)
- A T Lonchakov
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620108, Yekaterinburg, Russia
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31
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Chen B, Fei F, Zhang D, Zhang B, Liu W, Zhang S, Wang P, Wei B, Zhang Y, Zuo Z, Guo J, Liu Q, Wang Z, Wu X, Zong J, Xie X, Chen W, Sun Z, Wang S, Zhang Y, Zhang M, Wang X, Song F, Zhang H, Shen D, Wang B. Intrinsic magnetic topological insulator phases in the Sb doped MnBi 2Te 4 bulks and thin flakes. Nat Commun 2019; 10:4469. [PMID: 31578337 PMCID: PMC6775157 DOI: 10.1038/s41467-019-12485-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 09/12/2019] [Indexed: 11/29/2022] Open
Abstract
Magnetic topological insulators (MTIs) offer a combination of topologically nontrivial characteristics and magnetic order and show promise in terms of potentially interesting physical phenomena such as the quantum anomalous Hall (QAH) effect and topological axion insulating states. However, the understanding of their properties and potential applications have been limited due to a lack of suitable candidates for MTIs. Here, we grow two-dimensional single crystals of Mn(SbxBi(1-x))2Te4 bulk and exfoliate them into thin flakes in order to search for intrinsic MTIs. We perform angle-resolved photoemission spectroscopy, low-temperature transport measurements, and first-principles calculations to investigate the band structure, transport properties, and magnetism of this family of materials, as well as the evolution of their topological properties. We find that there exists an optimized MTI zone in the Mn(SbxBi(1-x))2Te4 phase diagram, which could possibly host a high-temperature QAH phase, offering a promising avenue for new device applications.
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Affiliation(s)
- Bo Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Fucong Fei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China.
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China.
| | - Dongqin Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Bo Zhang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, China
| | - Wanling Liu
- Division of Photon Science and Condensed Matter Physics, School of Physical Science and Technology, ShanghaiTech University, 200031, Shanghai, China
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 200050, Shanghai, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Shuai Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Pengdong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, China
| | - Boyuan Wei
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Yong Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Zewen Zuo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Jingwen Guo
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Qianqian Liu
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Zilu Wang
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - Xuchuan Wu
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - Junyu Zong
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Xuedong Xie
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Wang Chen
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Zhe Sun
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029, Hefei, China
| | - Shancai Wang
- Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, 100872, Beijing, China
| | - Yi Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
| | - Minhao Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
| | - Xuefeng Wang
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and School of Electronic Science and Engineering, Nanjing University, 210093, Nanjing, China
| | - Fengqi Song
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China.
- Atomic Manufacture Institute (AMI), 211805, Nanjing, China.
| | - Haijun Zhang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China.
| | - Dawei Shen
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, 200050, Shanghai, China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, 100049, Beijing, China.
| | - Baigeng Wang
- National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, and College of Physics, Nanjing University, 210093, Nanjing, China
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32
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Huang Z, Zhang D. Bandgap engineering of PbTe ultra-thin layers by surface passivations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:295503. [PMID: 30925485 DOI: 10.1088/1361-648x/ab14ac] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We calculate the electronic structures of the PbTe (1 1 1) ultra-thin films by performing the first-principles calculations. The PbTe (1 1 1) ultra-thin films possess direct or indirect band gaps depending sensitively on surface passivations with hydrogen or halogen atoms, and the band gaps depend sensitively on the passivation elements. The bandgaps of PbTe (1 1 1) ultra-thin films with hydrogen passivations can be tuned from 15 meV to 65 meV by applying external strains, making PbTe ultra-thin films promising candidates for optoelectronic device applications in terahertz regime.
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Affiliation(s)
- Zhihan Huang
- SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, 100083 Beijing, People's Republic of China. College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, 100049 Beijing, People's Republic of China
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33
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Zhang D, Shi M, Zhu T, Xing D, Zhang H, Wang J. Topological Axion States in the Magnetic Insulator MnBi_{2}Te_{4} with the Quantized Magnetoelectric Effect. PHYSICAL REVIEW LETTERS 2019; 122:206401. [PMID: 31172761 DOI: 10.1103/physrevlett.122.206401] [Citation(s) in RCA: 181] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/24/2019] [Indexed: 06/09/2023]
Abstract
Topological states of quantum matter have attracted great attention in condensed matter physics and materials science. The study of time-reversal-invariant topological states in quantum materials has made tremendous progress. However, the study of magnetic topological states falls much behind due to the complex magnetic structures. Here, we predict the tetradymite-type compound MnBi_{2}Te_{4} and its related materials host topologically nontrivial magnetic states. The magnetic ground state of MnBi_{2}Te_{4} is an antiferromagetic topological insulator state with a large topologically nontrivial energy gap (∼0.2 eV). It presents the axion state, which has gapped bulk and surface states, and the quantized topological magnetoelectric effect. The ferromagnetic phase of MnBi_{2}Te_{4} might lead to a minimal ideal Weyl semimetal.
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Affiliation(s)
- Dongqin Zhang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Minji Shi
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Tongshuai Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Dingyu Xing
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Haijun Zhang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jing Wang
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
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34
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Lau A, Ortix C. Topological Semimetals in the SnTe Material Class: Nodal Lines and Weyl Points. PHYSICAL REVIEW LETTERS 2019; 122:186801. [PMID: 31144876 DOI: 10.1103/physrevlett.122.186801] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 07/30/2018] [Indexed: 06/09/2023]
Abstract
We theoretically show that IV-VI semiconducting compounds with low-temperature rhombohedral crystal structure represent a new potential platform for topological semimetals. By means of minimal k·p models, we find that the two-step structural symmetry reduction of the high-temperature rocksalt crystal structure, comprising a rhombohedral distortion along the [111] direction followed by a relative shift of the cation and anion sublattices, gives rise to topologically protected Weyl semimetal and nodal line semimetal phases. We derive general expressions for the nodal features and apply our results to SnTe, showing explicitly how Weyl points and nodal lines emerge in this system. Experimentally, the topological semimetals could potentially be realized in the low-temperature ferroelectric phase of SnTe, GeTe, and related alloys.
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Affiliation(s)
- Alexander Lau
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 4056, 2600 GA Delft, Netherlands
| | - Carmine Ortix
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, Netherlands
- Dipartimento di Fisica "E. R. Caianiello," Universitá di Salerno, IT-84084 Fisciano, Italy
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35
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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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36
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Yesilyurt C, Siu ZB, Tan SG, Liang G, Yang SA, Jalil MBA. Electrically tunable valley polarization in Weyl semimetals with tilted energy dispersion. Sci Rep 2019; 9:4480. [PMID: 30872691 PMCID: PMC6418200 DOI: 10.1038/s41598-019-40947-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 02/18/2019] [Indexed: 11/16/2022] Open
Abstract
Tunneling transport across electrical potential barriers in Weyl semimetals with tilted energy dispersion is investigated. We report that the electrons around different valleys experience opposite direction refractions at the barrier interface when the energy dispersion is tilted along one of the transverse directions. Chirality dependent refractions at the barrier interface polarize the Weyl fermions in angle-space according to their valley index. A real magnetic barrier configuration is used to select allowed transmission angles, which results in electrically controllable and switchable valley polarization. Our findings may pave the way for experimental investigation of valley polarization, as well as valleytronic and electron optic applications in Weyl semimetals.
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Affiliation(s)
- Can Yesilyurt
- Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Republic of Singapore.
| | - Zhuo Bin Siu
- Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Republic of Singapore
| | - Seng Ghee Tan
- Department of Optoelectric Physics, Chinese Culture University, Taipei, 11114, Taiwan
| | - Gengchiau Liang
- Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Republic of Singapore
| | - Shengyuan A Yang
- Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore
| | - Mansoor B A Jalil
- Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Republic of Singapore.
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37
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Sukhachov PO, Gorbar EV, Shovkovy IA, Miransky VA. Inter-node superconductivity in strained Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:055602. [PMID: 30523810 DOI: 10.1088/1361-648x/aaf12a] [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
The effects of a strain-induced pseudomagnetic field on inter-node spin-triplet superconducting states in Weyl semimetals are studied by using the quasiclassical Eilenberger formalism. It is found that the Cooper pairing with spins parallel to the pseudomagnetic field has the lowest energy among the spin-triplet states and its gap does not depend on the strength of the field. In such a state, both electric and chiral superconducting currents are absent. This is in contrast to the superconducting states with the spins of Cooper pairs normal to the field, which support a nonzero chiral current and are inhibited by the strain-induced pseudomagnetic field. The corresponding critical value of the field, which separates the normal and superconducting phases, is estimated.
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Affiliation(s)
- P O Sukhachov
- Department of Applied Mathematics, Western University, London, Ontario, N6A 5B7, Canada
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38
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Zhang SB, Erdmenger J, Trauzettel B. Chirality Josephson Current Due to a Novel Quantum Anomaly in Inversion-Asymmetric Weyl Semimetals. PHYSICAL REVIEW LETTERS 2018; 121:226604. [PMID: 30547657 DOI: 10.1103/physrevlett.121.226604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/21/2018] [Indexed: 06/09/2023]
Abstract
We study Josephson junctions based on inversion-asymmetric but time-reversal symmetric Weyl semimetals under the influence of Zeeman fields. We find that, due to distinct spin textures, the Weyl nodes of opposite chirality respond differently to an external magnetic field. Remarkably, a Zeeman field perpendicular to the junction direction results in a phase shift of opposite sign in the current-phase relations of opposite chirality. This leads to a finite chirality Josephson current (CJC) even in the absence of a phase difference across the junction. This feature could allow for applications in chiralitytronics. In the long junction and zero temperature limit, the CJC embodies a novel quantum anomaly of Goldstone bosons at π phase difference which is associated with a Z_{2} symmetry at low energies. It can be detected experimentally via an anomalous Fraunhofer pattern.
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Affiliation(s)
- Song-Bo Zhang
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany
| | - Johanna Erdmenger
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany
| | - Björn Trauzettel
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, D-97074 Würzburg, Germany
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Flötotto D, Bai Y, Chan YH, Chen P, Wang X, Rossi P, Xu CZ, Zhang C, Hlevyack JA, Denlinger JD, Hong H, Chou MY, Mittemeijer EJ, Eckstein JN, Chiang TC. In Situ Strain Tuning of the Dirac Surface States in Bi 2Se 3 Films. NANO LETTERS 2018; 18:5628-5632. [PMID: 30109804 DOI: 10.1021/acs.nanolett.8b02105] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Elastic strain has the potential for a controlled manipulation of the band gap and spin-polarized Dirac states of topological materials, which can lead to pseudomagnetic field effects, helical flat bands, and topological phase transitions. However, practical realization of these exotic phenomena is challenging and yet to be achieved. Here we show that the Dirac surface states of the topological insulator Bi2Se3 can be reversibly tuned by an externally applied elastic strain. Performing in situ X-ray diffraction and in situ angle-resolved photoemission spectroscopy measurements during tensile testing of epitaxial Bi2Se3 films bonded onto a flexible substrate, we demonstrate elastic strains of up to 2.1% and quantify the resulting changes in the topological surface state. Our study establishes the functional relationship between the lattice and electronic structures of Bi2Se3 and, more generally, demonstrates a new route toward momentum-resolved mapping of strain-induced band structure changes.
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Affiliation(s)
- David Flötotto
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Yang Bai
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Yang-Hao Chan
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
| | - Peng Chen
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Xiaoxiong Wang
- College of Science , Nanjing University of Science and Technology , Nanjing 210094 , China
| | - Paul Rossi
- Max Planck Institute for Intelligent Systems , Heisenbergstraße 3 , D-70569 Stuttgart , Germany
| | - Cai-Zhi Xu
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Can Zhang
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Joseph A Hlevyack
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Jonathan D Denlinger
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Hawoong Hong
- Advanced Photon Source , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Mei-Yin Chou
- Institute of Atomic and Molecular Sciences , Academia Sinica , Taipei 10617 , Taiwan
- School of Physics , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
- Department of Physics , National Taiwan University , Taipei 10617 , Taiwan
| | - Eric J Mittemeijer
- Max Planck Institute for Intelligent Systems , Heisenbergstraße 3 , D-70569 Stuttgart , Germany
- Institute for Materials Science , University of Stuttgart , Germany
| | - James N Eckstein
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Tai-Chang Chiang
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Frederick Seitz Materials Research Laboratory , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
- Department of Physics , National Taiwan University , Taipei 10617 , Taiwan
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40
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Sun XQ, Zhang SC, Bzdušek T. Conversion Rules for Weyl Points and Nodal Lines in Topological Media. PHYSICAL REVIEW LETTERS 2018; 121:106402. [PMID: 30240246 DOI: 10.1103/physrevlett.121.106402] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Indexed: 06/08/2023]
Abstract
According to a widely held paradigm, a pair of Weyl points with opposite chirality mutually annihilate when brought together. In contrast, we show that such a process is strictly forbidden for Weyl points related by a mirror symmetry, provided that an effective two-band description exists in terms of orbitals with opposite mirror eigenvalue. Instead, such a pair of Weyl points convert into a nodal loop inside a symmetric plane upon the collision. Similar constraints are identified for systems with multiple mirrors, facilitating previously unreported nodal-line and nodal-chain semimetals that exhibit both Fermi-arc and drumhead surface states. We further find that Weyl points in systems symmetric under a π rotation composed with time reversal are characterized by an additional integer charge that we call helicity. A pair of Weyl points with opposite chirality can annihilate only if their helicities also cancel out. We base our predictions on topological crystalline invariants derived from relative homotopy theory, and we test our predictions on simple tight-binding models. The outlined homotopy description can be directly generalized to systems with multiple bands and other choices of symmetry.
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Affiliation(s)
- Xiao-Qi Sun
- Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA
- Stanford Center for Topological Quantum Physics, Stanford University, Stanford, California 94305-4045, USA
| | - Shou-Cheng Zhang
- Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA
- Stanford Center for Topological Quantum Physics, Stanford University, Stanford, California 94305-4045, USA
| | - Tomáš Bzdušek
- Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA
- Stanford Center for Topological Quantum Physics, Stanford University, Stanford, California 94305-4045, USA
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41
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Owerre SA. Strain-induced topological magnon phase transitions: applications to kagome-lattice ferromagnets. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:245803. [PMID: 29741490 DOI: 10.1088/1361-648x/aac365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A common feature of topological insulators is that they are characterized by topologically invariant quantity such as the Chern number and the [Formula: see text] index. This quantity distinguishes a nontrivial topological system from a trivial one. A topological phase transition may occur when there are two topologically distinct phases, and it is usually defined by a gap closing point where the topologically invariant quantity is ill-defined. In this paper, we show that the magnon bands in the strained (distorted) kagome-lattice ferromagnets realize an example of a topological magnon phase transition in the realistic parameter regime of the system. When spin-orbit coupling (SOC) is neglected (i.e. no Dzyaloshinskii-Moriya interaction), we show that all three magnon branches are dispersive with no flat band, and there exists a critical point where tilted Dirac and semi-Dirac point coexist in the magnon spectra. The critical point separates two gapless magnon phases as opposed to the usual phase transition. Upon the inclusion of SOC, we realize a topological magnon phase transition point at the critical strain [Formula: see text], where D and J denote the perturbative SOC and the Heisenberg spin exchange interaction respectively. It separates two distinct topological magnon phases with different Chern numbers for [Formula: see text] and for [Formula: see text]. The associated anomalous thermal Hall conductivity develops an abrupt change at [Formula: see text], due to the divergence of the Berry curvature in momentum space. The proposed topological magnon phase transition is experimentally feasible by applying external perturbations such as uniaxial strain or pressure.
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Affiliation(s)
- S A Owerre
- Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario N2L 2Y5, Canada
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42
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Huang T, Ma T, Wang LG. Zitterbewegung in time-reversal Weyl semimetals. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:245501. [PMID: 29722679 DOI: 10.1088/1361-648x/aac23b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We perform a systematic study of the Zitterbewegung effect of fermions, which are described by a Gaussian wave with broken spatial-inversion symmetry in a three-dimensional low-energy Weyl semimetal. Our results show that the motion of fermions near the Weyl points is characterized by rectilinear motion and Zitterbewegung oscillation. The ZB oscillation is affected by the width of the Gaussian wave packet, the position of the Weyl node, and the chirality and anisotropy of the fermions. By introducing a one-dimensional cosine potential, the new generated massless fermions have lower Fermi velocities, which results in a robust relativistic oscillation. Modulating the height and periodicity of periodic potential demonstrates that the ZB effect of fermions in the different Brillouin zones exhibits quasi-periodic behavior. These results may provide an appropriate system for probing the Zitterbewegung effect experimentally.
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Affiliation(s)
- Tongyun Huang
- Department of Physics, Beijing Normal University, Beijing 100875, People's Republic of China
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43
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Abstract
Surface or bulk Fermi arcs are engineered in photonic structures to connect ideal Weyl points or exceptional points
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Affiliation(s)
- Şahin K Özdemir
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA.
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44
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Yang B, Guo Q, Tremain B, Liu R, Barr LE, Yan Q, Gao W, Liu H, Xiang Y, Chen J, Fang C, Hibbins A, Lu L, Zhang S. Ideal Weyl points and helicoid surface states in artificial photonic crystal structures. Science 2018; 359:1013-1016. [DOI: 10.1126/science.aaq1221] [Citation(s) in RCA: 188] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/19/2017] [Indexed: 11/02/2022]
Affiliation(s)
- Biao Yang
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
| | - Qinghua Guo
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
- International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, China
| | - Ben Tremain
- Electromagnetic and Acoustic Materials Group, Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Rongjuan Liu
- Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
| | - Lauren E. Barr
- Electromagnetic and Acoustic Materials Group, Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Qinghui Yan
- Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
| | - Wenlong Gao
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
| | - Hongchao Liu
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
| | - Yuanjiang Xiang
- International Collaborative Laboratory of 2D Materials for Optoelectronic Science and Technology of Ministry of Education, Shenzhen University, Shenzhen 518060, China
| | - Jing Chen
- School of Physics, Nankai University, Tianjin 300071, China
| | - Chen Fang
- Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
| | - Alastair Hibbins
- Electromagnetic and Acoustic Materials Group, Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK
| | - Ling Lu
- Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China
| | - Shuang Zhang
- School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
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45
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Kharitonov M, Mayer JB, Hankiewicz EM. Universality and Stability of the Edge States of Chiral-Symmetric Topological Semimetals and Surface States of the Luttinger Semimetal. PHYSICAL REVIEW LETTERS 2017; 119:266402. [PMID: 29328715 DOI: 10.1103/physrevlett.119.266402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Indexed: 06/07/2023]
Abstract
We theoretically demonstrate that the chiral structure of the nodes of nodal semimetals is responsible for the existence and universal local properties of the edge states in the vicinity of the nodes. We perform a general analysis of the edge states for an isolated node of a 2D semimetal, protected by chiral symmetry and characterized by the topological winding number N. We derive the asymptotic chiral-symmetric boundary conditions and find that there are N+1 universal classes of them. The class determines the numbers of flatband edge states on either side off the node in the 1D spectrum and the winding number N gives the total number of edge states. We then show that the edge states of chiral nodal semimetals are robust: they persist in a finite-size stability region of parameters of chiral-asymmetric terms. This significantly extends the notion of 2D and 3D topological nodal semimetals. We demonstrate that the Luttinger model with a quadratic node for j=3/2 electrons is a 3D topological semimetal in this new sense and predict that α-Sn, HgTe, possibly Pr_{2}Ir_{2}O_{7}, and many other semimetals described by it are topological and exhibit surface states.
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Affiliation(s)
- Maxim Kharitonov
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany
| | - Julian-Benedikt Mayer
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany
| | - Ewelina M Hankiewicz
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, 97074 Würzburg, Germany
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46
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Wang J, Zhang SC. Topological states of condensed matter. NATURE MATERIALS 2017; 16:1062-1067. [PMID: 29066825 DOI: 10.1038/nmat5012] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Accepted: 09/24/2017] [Indexed: 06/07/2023]
Abstract
Topological states of quantum matter have been investigated intensively in recent years in materials science and condensed matter physics. The field developed explosively largely because of the precise theoretical predictions, well-controlled materials processing, and novel characterization techniques. In this Perspective, we review recent progress in topological insulators, the quantum anomalous Hall effect, chiral topological superconductors, helical topological superconductors and Weyl semimetals.
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Affiliation(s)
- Jing Wang
- State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Shou-Cheng Zhang
- Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA
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47
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Nie S, Xu G, Prinz FB, Zhang SC. Topological semimetal in honeycomb lattice LnSI. Proc Natl Acad Sci U S A 2017; 114:10596-10600. [PMID: 28928149 PMCID: PMC5635928 DOI: 10.1073/pnas.1713261114] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recognized as elementary particles in the standard model, Weyl fermions in condensed matter have received growing attention. However, most of the previously reported Weyl semimetals exhibit rather complicated electronic structures that, in turn, may have raised questions regarding the underlying physics. Here, we report promising topological phases that can be realized in specific honeycomb lattices, including ideal Weyl semimetal structures, 3D strong topological insulators, and nodal-line semimetal configurations. In particular, we highlight a semimetal featuring both Weyl nodes and nodal lines. Guided by this model, we showed that GdSI, the long-perceived ideal Weyl semimetal, has two pairs of Weyl nodes residing at the Fermi level and that LuSI (YSI) is a 3D strong topological insulator with the right-handed helical surface states. Our work provides a mechanism to study topological semimetals and proposes a platform for exploring the physics of Weyl semimetals as well as related device designs.
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Affiliation(s)
- Simin Nie
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305
| | - Gang Xu
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China;
- School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Department of Physics, Stanford University, Stanford, CA 94305-4045
| | - Fritz B Prinz
- Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305
| | - Shou-Cheng Zhang
- Department of Physics, Stanford University, Stanford, CA 94305-4045
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48
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Yang H, Yu J, Parkin SSP, Felser C, Liu CX, Yan B. Prediction of Triple Point Fermions in Simple Half-Heusler Topological Insulators. PHYSICAL REVIEW LETTERS 2017; 119:136401. [PMID: 29341689 DOI: 10.1103/physrevlett.119.136401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Indexed: 06/07/2023]
Abstract
We predict the existence of triple point fermions in the band structure of several half-Heusler topological insulators by ab initio calculations and the Kane model. We find that many half-Heusler compounds exhibit multiple triple points along four independent C_{3} axes, through which the doubly degenerate conduction bands and the nondegenerate valence band cross each other linearly nearby the Fermi energy. When projected from the bulk to the (111) surface, most of these triple points are located far away from the surface Γ[over ¯] point, as distinct from previously reported triple point fermion candidates. These isolated triple points give rise to Fermi arcs on the surface, that can be readily detected by photoemission spectroscopy or scanning tunneling spectroscopy.
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Affiliation(s)
- Hao Yang
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Jiabin Yu
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Stuart S P Parkin
- Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - Chao-Xing Liu
- Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
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49
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Wang CM, Sun HP, Lu HZ, Xie XC. 3D Quantum Hall Effect of Fermi Arcs in Topological Semimetals. PHYSICAL REVIEW LETTERS 2017; 119:136806. [PMID: 29341701 DOI: 10.1103/physrevlett.119.136806] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Indexed: 06/07/2023]
Abstract
The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Hall effect. Via a "wormhole" tunneling assisted by the Weyl nodes, the Fermi arcs at opposite surfaces can form a complete Fermi loop and support the quantum Hall effect. The edge states of the Fermi arcs show a unique 3D distribution, giving an example of (d-2)-dimensional boundary states. This is distinctly different from the surface-state quantum Hall effect from a single surface of topological insulator. As the Fermi energy sweeps through the Weyl nodes, the sheet Hall conductivity evolves from the 1/B dependence to quantized plateaus at the Weyl nodes. This behavior can be realized by tuning gate voltages in a slab of topological semimetal, such as the TaAs family, Cd_{3}As_{2}, or Na_{3}Bi. This work will be instructive not only for searching transport signatures of the Fermi arcs but also for exploring novel electron gases in other topological phases of matter.
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Affiliation(s)
- C M Wang
- Institute for Quantum Science and Engineering and Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China
- School of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - Hai-Peng Sun
- 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
| | - 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
| | - 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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50
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Lau A, Koepernik K, van den Brink J, Ortix C. Generic Coexistence of Fermi Arcs and Dirac Cones on the Surface of Time-Reversal Invariant Weyl Semimetals. PHYSICAL REVIEW LETTERS 2017; 119:076801. [PMID: 28949688 DOI: 10.1103/physrevlett.119.076801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Indexed: 06/07/2023]
Abstract
The hallmark of Weyl semimetals is the existence of open constant-energy contours on their surface-the so-called Fermi arcs-connecting Weyl points. Here, we show that, for time-reversal symmetric realizations of Weyl semimetals, these Fermi arcs, in many cases, coexist with closed Fermi pockets originating from surface Dirac cones pinned to time-reversal invariant momenta. The existence of Fermi pockets is required for certain Fermi-arc connectivities due to additional restrictions imposed by the six Z_{2} topological invariants characterizing a generic time-reversal invariant Weyl semimetal. We show that a change of the Fermi-arc connectivity generally leads to a different topology of the surface Fermi surface and identify the half-Heusler compound LaPtBi under in-plane compressive strain as a material that realizes this surface Lifshitz transition. We also discuss universal features of this coexistence in quasiparticle interference spectra.
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Affiliation(s)
- Alexander Lau
- Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany
| | - Klaus Koepernik
- Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany
| | - Jeroen van den Brink
- Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany
- Institute for Theoretical Physics, TU Dresden, 01069 Dresden, Germany
| | - Carmine Ortix
- Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, Netherlands
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