51
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Yao H, Zhu M, Jiang L, Zheng Y. Simulation on the electronic wave packet cyclotron motion in a Weyl semimetal slab. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:155502. [PMID: 28181913 DOI: 10.1088/1361-648x/aa5f94] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We perform a numerical simulation on the time evolution of an electronic wave packet in a Weyl semimetal (WSM) slab driven by a magnetic field. We find that the evolution trajectory of the wave packet depends sensitively on its initial spin state. Only with initial spin state identical to that of the Fermi arc state at the surface it localized, does the wave packet evolution demonstrate the characteristic cyclotron orbit of WSM previously predicted from a semiclassical viewpoint. By analyzing the eigen-expansion of the electronic wave packet, we find the chiral Landau levels (LLs) of the WSM slab, as ingredients of the wave packet, to be responsible for establishing the characteristic WSM cyclotron orbit. In contrast, the nonchiral LLs contribute irregular oscillations to the wave packet evolution, going against the formation of a well-defined cyclotron orbit. In addition, the tilted magnetic field does not affect the motion of the electronic wave packet along the Fermi arcs in the momentum space. It does, however, alter the evolution trajectory of the electronic wave packet in real space and spin space. Finally, the energy disalignment of the Weyl nodes results in a 3D cyclotron orbit in real space.
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Affiliation(s)
- Haibo Yao
- Department of Physics, Jilin University, Changchun 130012, People's Republic of China
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52
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Ma J, Pesin DA. Dynamic Chiral Magnetic Effect and Faraday Rotation in Macroscopically Disordered Helical Metals. PHYSICAL REVIEW LETTERS 2017; 118:107401. [PMID: 28339260 DOI: 10.1103/physrevlett.118.107401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Indexed: 06/06/2023]
Abstract
We develop an effective medium theory for electromagnetic wave propagation through gapless nonuniform systems with a dynamic chiral magnetic effect. The theory allows us to calculate macroscopic-disorder-induced corrections to the values of optical, as well as chiral magnetic conductivities. In particular, we show that spatial fluctuations of the optical conductivity induce corrections to the effective value of the chiral magnetic conductivity. The absolute value of the effect varies strongly depending on the system parameters, but yields the leading frequency dependence of the polarization rotation and circular dichroism signals. Experimentally, these corrections can be observed as features in the Faraday rotation angle near frequencies that correspond to the bulk plasmon resonances of a material. Such features are not expected to be present in single-crystal samples.
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Affiliation(s)
- J Ma
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
| | - D A Pesin
- Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
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53
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Xu N, Autès G, Matt CE, Lv BQ, Yao MY, Bisti F, Strocov VN, Gawryluk D, Pomjakushina E, Conder K, Plumb NC, Radovic M, Qian T, Yazyev OV, Mesot J, Ding H, Shi M. Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals. PHYSICAL REVIEW LETTERS 2017; 118:106406. [PMID: 28339253 DOI: 10.1103/physrevlett.118.106406] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Indexed: 06/06/2023]
Abstract
The Weyl semimetal phase is a recently discovered topological quantum state of matter characterized by the presence of topologically protected degeneracies near the Fermi level. These degeneracies are the source of exotic phenomena, including the realization of chiral Weyl fermions as quasiparticles in the bulk and the formation of Fermi arc states on the surfaces. Here, we demonstrate that these two key signatures show distinct evolutions with the bulk band topology by performing angle-resolved photoemission spectroscopy, supported by first-principles calculations, on transition-metal monophosphides. While Weyl fermion quasiparticles exist only when the chemical potential is located between two saddle points of the Weyl cone features, the Fermi arc states extend in a larger energy scale and are robust across the bulk Lifshitz transitions associated with the recombination of two nontrivial Fermi surfaces enclosing one Weyl point into a single trivial Fermi surface enclosing two Weyl points of opposite chirality. Therefore, in some systems (e.g., NbP), topological Fermi arc states are preserved even if Weyl fermion quasiparticles are absent in the bulk. Our findings not only provide insight into the relationship between the exotic physical phenomena and the intrinsic bulk band topology in Weyl semimetals, but also resolve the apparent puzzle of the different magnetotransport properties observed in TaAs, TaP, and NbP, where the Fermi arc states are similar.
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Affiliation(s)
- N Xu
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - G Autès
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - C E Matt
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - B Q Lv
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - M Y Yao
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - F Bisti
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - D Gawryluk
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - E Pomjakushina
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - K Conder
- Laboratory for Developments and Methods, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - T Qian
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - O V Yazyev
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - H Ding
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, China
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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54
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Niemann AC, Gooth J, Wu SC, Bäßler S, Sergelius P, Hühne R, Rellinghaus B, Shekhar C, Süß V, Schmidt M, Felser C, Yan B, Nielsch K. Chiral magnetoresistance in the Weyl semimetal NbP. Sci Rep 2017; 7:43394. [PMID: 28262790 PMCID: PMC5338026 DOI: 10.1038/srep43394] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/20/2017] [Indexed: 11/13/2022] Open
Abstract
NbP is a recently realized Weyl semimetal (WSM), hosting Weyl points through which conduction and valence bands cross linearly in the bulk and exotic Fermi arcs appear. The most intriguing transport phenomenon of a WSM is the chiral anomaly-induced negative magnetoresistance (NMR) in parallel electric and magnetic fields. In intrinsic NbP the Weyl points lie far from the Fermi energy, making chiral magneto-transport elusive. Here, we use Ga-doping to relocate the Fermi energy in NbP sufficiently close to the W2 Weyl points, for which the different Fermi surfaces are verified by resultant quantum oscillations. Consequently, we observe a NMR for parallel electric and magnetic fields, which is considered as a signature of the chiral anomaly in condensed-matter physics. The NMR survives up to room temperature, making NbP a versatile material platform for the development of Weyltronic applications.
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Affiliation(s)
- Anna Corinna Niemann
- Institute of Nanostructure and Solid State Physics, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg, Germany.,Leibniz Institute for Solid State and Materials Research Dresden, Institute for Metallic Materials, Helmholtzstraße 20, 01069 Dresden, Germany
| | - Johannes Gooth
- Institute of Nanostructure and Solid State Physics, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg, Germany.,IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Shu-Chun Wu
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Svenja Bäßler
- Institute of Nanostructure and Solid State Physics, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg, Germany
| | - Philip Sergelius
- Institute of Nanostructure and Solid State Physics, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg, Germany
| | - Ruben Hühne
- Leibniz Institute for Solid State and Materials Research Dresden, Institute for Metallic Materials, Helmholtzstraße 20, 01069 Dresden, Germany
| | - Bernd Rellinghaus
- Leibniz Institute for Solid State and Materials Research Dresden, Institute for Metallic Materials, Helmholtzstraße 20, 01069 Dresden, Germany
| | - Chandra Shekhar
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Vicky Süß
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Marcus Schmidt
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Binghai Yan
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany.,Max Planck Institute for Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
| | - Kornelius Nielsch
- Institute of Nanostructure and Solid State Physics, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg, Germany.,Leibniz Institute for Solid State and Materials Research Dresden, Institute for Metallic Materials, Helmholtzstraße 20, 01069 Dresden, Germany
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55
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Hübener H, Sentef MA, De Giovannini U, Kemper AF, Rubio A. Creating stable Floquet-Weyl semimetals by laser-driving of 3D Dirac materials. Nat Commun 2017; 8:13940. [PMID: 28094286 PMCID: PMC5247574 DOI: 10.1038/ncomms13940] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 11/15/2016] [Indexed: 12/23/2022] Open
Abstract
Tuning and stabilizing topological states, such as Weyl semimetals, Dirac semimetals or topological insulators, is emerging as one of the major topics in materials science. Periodic driving of many-body systems offers a platform to design Floquet states of matter with tunable electronic properties on ultrafast timescales. Here we show by first principles calculations how femtosecond laser pulses with circularly polarized light can be used to switch between Weyl semimetal, Dirac semimetal and topological insulator states in a prototypical three-dimensional (3D) Dirac material, Na3Bi. Our findings are general and apply to any 3D Dirac semimetal. We discuss the concept of time-dependent bands and steering of Floquet-Weyl points and demonstrate how light can enhance topological protection against lattice perturbations. This work has potential practical implications for the ultrafast switching of materials properties, such as optical band gaps or anomalous magnetoresistance.
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Affiliation(s)
- Hannes Hübener
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, San Sebastián 20018, Spain
| | - Michael A. Sentef
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, Hamburg 22761, Germany
| | - Umberto De Giovannini
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, San Sebastián 20018, Spain
- Dipartimento di Fisica e Chimica, Universitá degli Studi di Palermo, Via Archirafi 36, I-90123, Palermo, Italy
| | - Alexander F. Kemper
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Angel Rubio
- Nano-Bio Spectroscopy Group and ETSF, Universidad del País Vasco, CFM CSIC-UPV/EHU, San Sebastián 20018, Spain
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, Hamburg 22761, Germany
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56
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Yesilyurt C, Tan SG, Liang G, Jalil MBA. Klein tunneling in Weyl semimetals under the influence of magnetic field. Sci Rep 2016; 6:38862. [PMID: 27941894 PMCID: PMC5150982 DOI: 10.1038/srep38862] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 11/15/2016] [Indexed: 11/09/2022] Open
Abstract
Klein tunneling refers to the absence of normal backscattering of electrons even under the case of high potential barriers. At the barrier interface, the perfect matching of electron and hole wavefunctions enables a unit transmission probability for normally incident electrons. It is theoretically and experimentally well understood in two-dimensional relativistic materials such as graphene. Here we investigate the Klein tunneling effect in Weyl semimetals under the influence of magnetic field induced by ferromagnetic stripes placed at barrier boundaries. Our results show that the resonance of Fermi wave vector at specific barrier lengths gives rise to perfect transmission rings, i.e., three-dimensional analogue of the so-called magic transmission angles in two-dimensional Dirac semimetals. Besides, the transmission profile can be shifted by application of magnetic field in the central region, a property which may be utilized in electro-optic applications. When the applied potential is close to the Fermi level, a particular incident vector can be selected by tuning the magnetic field, thus enabling highly selective transmission of electrons in the bulk of Weyl semimetals. Our analytical and numerical calculations obtained by considering Dirac electrons in three regions and using experimentally feasible parameters can pave the way for relativistic tunneling 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
| | - Seng Ghee Tan
- Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore
- Data Storage Institute, Agency of Science, Technology and Research (A* Star), Singapore 138634, Republic of Singapore
| | - Gengchiau Liang
- Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore
| | - Mansoor B. A. Jalil
- Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Republic of Singapore
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57
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Resonance states and beating pattern induced by quantum impurity scattering in Weyl/Dirac semimetals. Sci Rep 2016; 6:36106. [PMID: 27808262 PMCID: PMC5093621 DOI: 10.1038/srep36106] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 10/10/2016] [Indexed: 11/09/2022] Open
Abstract
Currently, Weyl semimetals (WSMs) are drawing great interest as a new topological nontrivial phase. When most of the studies concentrated on the clean host WSMs, it is expected that the dirty WSM system would present rich physics due to the interplay between the WSM states and the impurities embedded inside these materials. We investigate theoretically the change of local density of states in three-dimensional Dirac and Weyl bulk states scattered off a quantum impurity. It is found that the quantum impurity scattering can create nodal resonance and Kondo peak/dip in the host bulk states, remarkably modifying the pristine spectrum structure. Moreover, the joint effect of the separation of Weyl nodes and the Friedel interference oscillation causes the unique battering feature. We in detail an- alyze the different contribution from the intra- and inter-node scattering processes and present various scenarios as a consequence of competition between them. Importantly, these behaviors are sensitive significantly to the displacement of Weyl nodes in energy or momentum, from which the distinctive fingerprints can be extracted to identify various semimetal materials experimentally by employing the scanning tunneling microscope.
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58
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Photonic crystals possessing multiple Weyl points and the experimental observation of robust surface states. Nat Commun 2016; 7:13038. [PMID: 27703140 PMCID: PMC5059475 DOI: 10.1038/ncomms13038] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 08/29/2016] [Indexed: 11/20/2022] Open
Abstract
Weyl points, as monopoles of Berry curvature in momentum space, have captured much attention recently in various branches of physics. Realizing topological materials that exhibit such nodal points is challenging and indeed, Weyl points have been found experimentally in transition metal arsenide and phosphide and gyroid photonic crystal whose structure is complex. If realizing even the simplest type of single Weyl nodes with a topological charge of 1 is difficult, then making a real crystal carrying higher topological charges may seem more challenging. Here we design, and fabricate using planar fabrication technology, a photonic crystal possessing single Weyl points (including type-II nodes) and multiple Weyl points with topological charges of 2 and 3. We characterize this photonic crystal and find nontrivial 2D bulk band gaps for a fixed kz and the associated surface modes. The robustness of these surface states against kz-preserving scattering is experimentally observed for the first time. To realize Weyl points carrying topological charges higher than one is challenging. Here, Chen et al. report a photonic crystal possessing single and multiple Weyl points with topological charges of two and three using planar fabrication technology.
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59
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Ahn S, Hwang EH, Min H. Collective modes in multi-Weyl semimetals. Sci Rep 2016; 6:34023. [PMID: 27687770 PMCID: PMC5043176 DOI: 10.1038/srep34023] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 09/06/2016] [Indexed: 11/13/2022] Open
Abstract
We investigate collective modes in three dimensional (3D) gapless multi-Weyl semimetals with anisotropic energy band dispersions (i.e., with a positive integer J). For comparison, we also consider the gapless semimetals with the isotropic band dispersions (i.e. E ~ kJ). We calculate analytically long-wavelength plasma frequencies incorporating interband transitions and chiral properties of carriers. For both the isotropic and anisotropic cases, we find that interband transitions and chirality lead to the depolarization shift of plasma frequencies. For the isotropic parabolic band dispersion the long-wavelength plasmons do not decay via Landau damping, while for the higher-order band dispersions the long-wavelength plasmons experience damping below a critical density. For systems with the anisotropic dispersion the density dependence of the long-wavelength plasma frequency along the direction of non-linear dispersion behaves like that of the isotropic linear band model, while along the direction of linear dispersion it behaves like that of the isotropic non-linear model. Plasmons along both directions remain undamped over a broad range of densities due to the chirality induced depolarization shift. Our results provide a comprehensive picture of how band dispersion and chirality affect plasmon behaviors in 3D gapless chiral systems with the arbitrary band dispersion.
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Affiliation(s)
- Seongjin Ahn
- Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 08826, Korea
| | - E. H. Hwang
- SKKU Advanced Institute of Nanotechnology and Department of Physics, Sungkyunkwan University, Suwon, 440-746, Korea
| | - Hongki Min
- Department of Physics and Astronomy and Center for Theoretical Physics, Seoul National University, Seoul 08826, Korea
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60
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Berry phase and band structure analysis of the Weyl semimetal NbP. Sci Rep 2016; 6:33859. [PMID: 27667203 PMCID: PMC5036179 DOI: 10.1038/srep33859] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/04/2016] [Indexed: 11/08/2022] Open
Abstract
Weyl semimetals are often considered the 3D-analogon of graphene or topological insulators. The evaluation of quantum oscillations in these systems remains challenging because there are often multiple conduction bands. We observe de Haas-van Alphen oscillations with several frequencies in a single crystal of the Weyl semimetal niobium phosphide. For each fundamental crystal axis, we can fit the raw data to a superposition of sinusoidal functions, which enables us to calculate the characteristic parameters of all individual bulk conduction bands using Fourier transform with an analysis of the temperature and magnetic field-dependent oscillation amplitude decay. Our experimental results indicate that the band structure consists of Dirac bands with low cyclotron mass, a non-trivial Berry phase and parabolic bands with a higher effective mass and trivial Berry phase.
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61
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Roy B, Juričić V, Das Sarma S. Universal optical conductivity of a disordered Weyl semimetal. Sci Rep 2016; 6:32446. [PMID: 27573668 PMCID: PMC5004158 DOI: 10.1038/srep32446] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 08/03/2016] [Indexed: 11/09/2022] Open
Abstract
Topological Weyl semimetals, besides manifesting chiral anomaly, can also accommodate a disorder-driven unconventional quantum phase transition into a metallic phase. A fundamentally and practically important question in this regard concerns an experimentally measurable quantity that can clearly distinguish these two phases. We show that the optical conductivity while serving this purpose can also play the role of a bonafide order parameter across such disorder-driven semimetal-metal quantum phase transition by virtue of displaying distinct scaling behavior in the semimetallic and metallic phases, as well as inside the quantum critical fan supporting a non-Fermi liquid. We demonstrate that the correction to the dielectric constant and optical conductivity in a dirty Weyl semimetal due to weak disorder is independent of the actual nature of point-like impurity scatterers. Therefore, optical conductivity can be used as an experimentally measurable quantity to study the critical properties and to pin the universality class of the disorder-driven quantum phase transition in Weyl semimetals.
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Affiliation(s)
- Bitan Roy
- Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Vladimir Juričić
- Nordita, Center for Quantum Materials, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, 10691 Stockholm, Sweden
| | - Sankar Das Sarma
- Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA
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62
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Wang CM, Lu HZ, Shen SQ. Anomalous Phase Shift of Quantum Oscillations in 3D Topological Semimetals. PHYSICAL REVIEW LETTERS 2016; 117:077201. [PMID: 27563993 DOI: 10.1103/physrevlett.117.077201] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 06/06/2023]
Abstract
Berry phase physics is closely related to a number of topological states of matter. Recently discovered topological semimetals are believed to host a nontrivial π Berry phase to induce a phase shift of ±1/8 in the quantum oscillation (+ for hole and - for electron carriers). We theoretically study the Shubnikov-de Haas oscillation of Weyl and Dirac semimetals, taking into account their topological nature and inter-Landau band scattering. For a Weyl semimetal with broken time-reversal symmetry, the phase shift is found to change nonmonotonically and go beyond known values of ±1/8 and ±5/8, as a function of the Fermi energy. For a Dirac semimetal or paramagnetic Weyl semimetal, time-reversal symmetry leads to a discrete phase shift of ±1/8 or ±5/8. Different from the previous works, we find that the topological band inversion can lead to beating patterns in the absence of Zeeman splitting. We also find the resistivity peaks should be assigned integers in the Landau index plot. Our findings may account for recent experiments in Cd_{2}As_{3} and should be helpful for exploring the Berry phase in various 3D systems.
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Affiliation(s)
- C M Wang
- 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
| | - Hai-Zhou Lu
- Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China
| | - Shun-Qing Shen
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China
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63
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Autès G, Gresch D, Troyer M, Soluyanov AA, Yazyev OV. Robust Type-II Weyl Semimetal Phase in Transition Metal Diphosphides XP_{2} (X=Mo, W). PHYSICAL REVIEW LETTERS 2016; 117:066402. [PMID: 27541470 DOI: 10.1103/physrevlett.117.066402] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Indexed: 06/06/2023]
Abstract
The recently discovered type-II Weyl points appear at the boundary between electron and hole pockets. Type-II Weyl semimetals that host such points are predicted to exhibit a new type of chiral anomaly and possess thermodynamic properties very different from their type-I counterparts. In this Letter, we describe the prediction of a type-II Weyl semimetal phase in the transition metal diphosphides MoP_{2} and WP_{2}. These materials are characterized by relatively simple band structures with four pairs of type-II Weyl points. Neighboring Weyl points have the same chirality, which makes the predicted topological phase robust with respect to small perturbations of the crystalline lattice. In addition, this peculiar arrangement of the Weyl points results in long topological Fermi arcs, thus making them readily accessible in angle-resolved photoemission spectroscopy.
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Affiliation(s)
- G Autès
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - D Gresch
- Theoretical Physics and Station Q Zurich, ETH Zurich, 8093 Zurich, Switzerland
| | - M Troyer
- Theoretical Physics and Station Q Zurich, ETH Zurich, 8093 Zurich, Switzerland
| | - A A Soluyanov
- Theoretical Physics and Station Q Zurich, ETH Zurich, 8093 Zurich, Switzerland
- Department of Physics, St. Petersburg State University, St. Petersburg 199034, Russia
| | - O V Yazyev
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- National Centre for Computational Design and Discovery of Novel Materials MARVEL, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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64
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Weng H, Dai X, Fang Z. Topological semimetals predicted from first-principles calculations. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:303001. [PMID: 27269048 DOI: 10.1088/0953-8984/28/30/303001] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have given a summary on our theoretical predictions of three kinds of topological semimetals (TSMs), namely, Dirac semimetal (DSM), Weyl semimetal (WSM) and node-line semimetal (NLSM). TSMs are new states of quantum matter, which are different from topological insulators. They are characterized by the topological stability of the Fermi surface, whether it encloses band crossing points, i.e. Dirac cone-like energy nodes, or not. They are distinguished from each other by the degeneracy and momentum space distribution of the nodal points. To realize these intriguing topological quantum states is quite challenging and crucial to both fundamental science and future application. Na3Bi and Cd3As2 were theoretically predicted to be DSM in 2012 and 2013 respectively. Their experimental verification in 2014 have ignited intensive studies on TSMs. The subsequent theoretical prediction of a nonmagnetic WSM in the TaAs family stimulated a second wave and many experimental works were released out in 2015. In 2014, a kind of three dimensional crystal of carbon was proposed to be an NLSM due to negligible spin-orbit coupling and coexistence of time-reversal and inversion symmetry. Though the final experimental confirmation of NLSM is still missing, there have been several theoretical proposals, including Cu3PdN from us. In the final part, we have summarized the whole family of TSMs and their relationships.
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Affiliation(s)
- Hongming Weng
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. Collaborative Innovation Center of Quantum Matter, Beijing, People's Republic of China
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Liu J, Hu J, Cao H, Zhu Y, Chuang A, Graf D, Adams DJ, Radmanesh SMA, Spinu L, Chiorescu I, Mao Z. Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2. Sci Rep 2016; 6:30525. [PMID: 27466151 PMCID: PMC4964361 DOI: 10.1038/srep30525] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/04/2016] [Indexed: 11/09/2022] Open
Abstract
Layered compounds AMnBi2 (A = Ca, Sr, Ba, or rare earth element) have been established as Dirac materials. Dirac electrons generated by the two-dimensional (2D) Bi square net in these materials are normally massive due to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes. Here we report that the Sb square net in an isostructural compound BaMnSb2 can host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH) oscillations in this material. From the analyses of the SdH oscillations, we find key signatures of Dirac fermions, including light effective mass (~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm(2)V(-1)S(-1)) and a π Berry phase accumulated along cyclotron orbit. Compared with AMnBi2, BaMnSb2 also exhibits much more significant quasi two-dimensional (2D) electronic structure, with the out-of-plane transport showing nonmetallic conduction below 120 K and the ratio of the out-of-plane and in-plane resistivity reaching ~670. Additionally, BaMnSb2 also exhibits a G-type antiferromagnetic order below 283 K. The combination of nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless Dirac electrons.
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Affiliation(s)
- Jinyu Liu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70018, USA
| | - Jin Hu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70018, USA
| | - Huibo Cao
- Quantum Condensed Matter Division, Oak Ridge National Laboratory, TN 37830, USA
| | - Yanglin Zhu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70018, USA
| | - Alyssa Chuang
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70018, USA
| | - D. Graf
- National High Magnetic Field Lab, Tallahassee, FL 32310, USA
| | - D. J. Adams
- Department of Physics and Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148, USA
| | - S. M. A. Radmanesh
- Department of Physics and Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148, USA
| | - L. Spinu
- Department of Physics and Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148, USA
| | - I. Chiorescu
- National High Magnetic Field Lab, Tallahassee, FL 32310, USA
- Department of Physics, Florida State University, Tallahassee, FL 32306, USA
| | - Zhiqiang Mao
- Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70018, USA
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Hu J, Tang Z, Liu J, Liu X, Zhu Y, Graf D, Myhro K, Tran S, Lau CN, Wei J, Mao Z. Evidence of Topological Nodal-Line Fermions in ZrSiSe and ZrSiTe. PHYSICAL REVIEW LETTERS 2016; 117:016602. [PMID: 27419579 DOI: 10.1103/physrevlett.117.016602] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Indexed: 06/06/2023]
Abstract
A Dirac nodal-line semimetal phase, which represents a new quantum state of topological materials, has been experimentally realized only in a few systems, including PbTaSe_{2}, PtSn_{4}, and ZrSiS. In this Letter, we report evidence of nodal-line fermions in ZrSiSe and ZrSiTe probed in de Haas-van Alphen quantum oscillations. Although ZrSiSe and ZrSiTe share a similar layered structure with ZrSiS, our studies show the Fermi surface (FS) enclosing a Dirac nodal line has a 2D character in ZrSiTe, in contrast with 3D-like FS in ZrSiSe and ZrSiS. Another important property revealed in our experiment is that the nodal-line fermion density in this family of materials (∼10^{20} cm^{-3}) is much higher than the Dirac fermion density of other topological materials with discrete nodes. In addition, we have demonstrated ZrSiSe and ZrSiTe single crystals can be thinned down to 2D atomic thin layers through microexfoliation, which offers the first platform to explore exotic properties of topological nodal-line fermions in low dimensions.
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Affiliation(s)
- Jin Hu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - Zhijie Tang
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - Jinyu Liu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - Xue Liu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - Yanglin Zhu
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - David Graf
- National High Magnetic Field Lab, Tallahassee, Florida 32310, USA
| | - Kevin Myhro
- Department of Physics, University of California, Riverside, California 92521, USA
| | - Son Tran
- Department of Physics, University of California, Riverside, California 92521, USA
| | - Chun Ning Lau
- Department of Physics, University of California, Riverside, California 92521, USA
| | - Jiang Wei
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - Zhiqiang Mao
- Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
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Chang G, Xu SY, Sanchez DS, Huang SM, Lee CC, Chang TR, Bian G, Zheng H, Belopolski I, Alidoust N, Jeng HT, Bansil A, Lin H, Hasan MZ. A strongly robust type II Weyl fermion semimetal state in Ta 3S 2. SCIENCE ADVANCES 2016; 2:e1600295. [PMID: 28861470 PMCID: PMC5566128 DOI: 10.1126/sciadv.1600295] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 05/23/2016] [Indexed: 05/12/2023]
Abstract
Weyl semimetals are of great interest because they provide the first realization of the Weyl fermion, exhibit exotic quantum anomalies, and host Fermi arc surface states. The separation between Weyl nodes of opposite chirality gives a measure of the robustness of the Weyl semimetal state. To exploit the novel phenomena that arise from Weyl fermions in applications, it is crucially important to find robust separated Weyl nodes. We propose a methodology to design robust Weyl semimetals with well-separated Weyl nodes. Using this methodology as a guideline, we search among the material parameter space and identify by far the most robust and ideal Weyl semimetal candidate in the single-crystalline compound tantalum sulfide (Ta3S2) with new and novel properties beyond TaAs. Crucially, our results show that Ta3S2 has the largest k-space separation between Weyl nodes among known Weyl semimetal candidates, which is about twice larger than the measured value in TaAs and 20 times larger than the predicted value in WTe2. Moreover, all Weyl nodes in Ta3S2 are of type II. Therefore, Ta3S2 is a type II Weyl semimetal. Furthermore, we predict that increasing the lattice by <4% can annihilate all Weyl nodes, driving a novel topological metal-to-insulator transition from a Weyl semimetal state to a topological insulator state. The robust type II Weyl semimetal state and the topological metal-to-insulator transition in Ta3S2 are potentially useful in device applications. Our methodology can be generally applied to search for new Weyl semimetals.
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Affiliation(s)
- Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research
Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546,
Singapore
- Department of Physics, National University of Singapore,
2 Science Drive 3, Singapore 117542, Singapore
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
| | - Daniel S. Sanchez
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research
Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546,
Singapore
- Department of Physics, National University of Singapore,
2 Science Drive 3, Singapore 117542, Singapore
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research
Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546,
Singapore
- Department of Physics, National University of Singapore,
2 Science Drive 3, Singapore 117542, Singapore
| | - Tay-Rong Chang
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
- Department of Physics, National Tsing Hua University,
Hsinchu 30013, Taiwan
| | - Guang Bian
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
| | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University,
Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei
11529, Taiwan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston,
MA 02115, USA
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research
Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546,
Singapore
- Department of Physics, National University of Singapore,
2 Science Drive 3, Singapore 117542, Singapore
| | - M. Zahid Hasan
- Laboratory for Topological Quantum Matter and
Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544,
USA
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68
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Bai C, Yang Y, Chang K. Chiral tunneling in gated inversion symmetric Weyl semimetal. Sci Rep 2016; 6:21283. [PMID: 26888491 PMCID: PMC4758052 DOI: 10.1038/srep21283] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 01/20/2016] [Indexed: 11/15/2022] Open
Abstract
Based on the chirality-resolved transfer-matrix method, we evaluate the chiral transport tunneling through Weyl semimetal multi-barrier structures created by periodic gates. It is shown that, in sharp contrast to the cases of three dimensional normal semimetals, the tunneling coefficient as a function of incident angle shows a strong anisotropic behavior. Importantly, the tunneling coefficients display an interesting periodic oscillation as a function of the crystallographic angle of the structures. With the increasement of the barriers, the tunneling current shows a Fabry-Perot type interferences. For superlattice structures, the fancy miniband effect has been revealed. Our results show that the angular dependence of the first bandgap can be reduced into a Lorentz formula. The disorder suppresses the oscillation of the tunneling conductance, but would not affect its average amplitude. This is in sharp contrast to that in multi-barrier conventional semiconductor structures. Moreover, numerical results for the dependence of the angularly averaged conductance on the incident energy and the structure parameters are presented and contrasted with those in two dimensional relativistic materials. Our work suggests that the gated Weyl semimetal opens a possible new route to access to new type nanoelectronic device.
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Affiliation(s)
- Chunxu Bai
- SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, People’s Republic of China
- School of Physics, Anyang Normal University, Anyang 455000, People’s Republic of China
| | - Yanling Yang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, People’s Republic of China
| | - Kai Chang
- SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, People’s Republic of China
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Chang TR, Xu SY, Chang G, Lee CC, Huang SM, Wang B, Bian G, Zheng H, Sanchez DS, Belopolski I, Alidoust N, Neupane M, Bansil A, Jeng HT, Lin H, Zahid Hasan M. Prediction of an arc-tunable Weyl Fermion metallic state in Mo(x)W(1-x)Te2. Nat Commun 2016; 7:10639. [PMID: 26875819 PMCID: PMC4756349 DOI: 10.1038/ncomms10639] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 01/07/2016] [Indexed: 12/25/2022] Open
Abstract
A Weyl semimetal is a new state of matter that hosts Weyl fermions as emergent quasiparticles. The Weyl fermions correspond to isolated points of bulk band degeneracy, Weyl nodes, which are connected only through the crystal's boundary by exotic Fermi arcs. The length of the Fermi arc gives a measure of the topological strength, because the only way to destroy the Weyl nodes is to annihilate them in pairs in the reciprocal space. To date, Weyl semimetals are only realized in the TaAs class. Here, we propose a tunable Weyl state in Mo(x)W(1-x)Te2 where Weyl nodes are formed by touching points between metallic pockets. We show that the Fermi arc length can be changed as a function of Mo concentration, thus tuning the topological strength. Our results provide an experimentally feasible route to realizing Weyl physics in the layered compound Mo(x)W(1-x)Te2, where non-saturating magneto-resistance and pressure-driven superconductivity have been observed.
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Affiliation(s)
- Tay-Rong Chang
- Department of Physics, National Tsing Hua University, 30013 Hsinchu, Taiwan
| | - Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - BaoKai Wang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
- Department of Physics, Northeastern University, Boston, 02115 Massachusetts, USA
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Daniel S. Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
| | - Madhab Neupane
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
- Condensed Matter and Magnet Science Group, Los Alamos National Laboratory, Los Alamos, 87545 New Mexico, USA
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, 02115 Massachusetts, USA
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, 30013 Hsinchu, Taiwan
- Institute of Physics, Academia Sinica, 11529 Taipei, Taiwan
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, 117546 Singapore, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542 Singapore, Singapore
| | - M. Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, 08544 New Jersey, USA
- Princeton Center for Complex Materials, Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, 08544 New Jersey, USA
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Huang SM, Xu SY, Belopolski I, Lee CC, Chang G, Chang TR, Wang B, Alidoust N, Bian G, Neupane M, Sanchez D, Zheng H, Jeng HT, Bansil A, Neupert T, Lin H, Hasan MZ. New type of Weyl semimetal with quadratic double Weyl fermions. Proc Natl Acad Sci U S A 2016; 113:1180-5. [PMID: 26787914 PMCID: PMC4747715 DOI: 10.1073/pnas.1514581113] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Weyl semimetals have attracted worldwide attention due to their wide range of exotic properties predicted in theories. The experimental realization had remained elusive for a long time despite much effort. Very recently, the first Weyl semimetal has been discovered in an inversion-breaking, stoichiometric solid TaAs. So far, the TaAs class remains the only Weyl semimetal available in real materials. To facilitate the transition of Weyl semimetals from the realm of purely theoretical interest to the realm of experimental studies and device applications, it is of crucial importance to identify other robust candidates that are experimentally feasible to be realized. In this paper, we propose such a Weyl semimetal candidate in an inversion-breaking, stoichiometric compound strontium silicide, SrSi2, with many new and novel properties that are distinct from TaAs. We show that SrSi2 is a Weyl semimetal even without spin-orbit coupling and that, after the inclusion of spin-orbit coupling, two Weyl fermions stick together forming an exotic double Weyl fermion with quadratic dispersions and a higher chiral charge of ±2. Moreover, we find that the Weyl nodes with opposite charges are located at different energies due to the absence of mirror symmetry in SrSi2, paving the way for the realization of the chiral magnetic effect. Our systematic results not only identify a much-needed robust Weyl semimetal candidate but also open the door to new topological Weyl physics that is not possible in TaAs.
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Affiliation(s)
- Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546; Department of Physics, National University of Singapore, Singapore 117542
| | - Su-Yang Xu
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544;
| | - Ilya Belopolski
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546; Department of Physics, National University of Singapore, Singapore 117542
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546; Department of Physics, National University of Singapore, Singapore 117542
| | - Tay-Rong Chang
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544; Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544
| | - BaoKai Wang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546; Department of Physics, National University of Singapore, Singapore 117542; Department of Physics, Northeastern University, Boston, MA 02115
| | - Nasser Alidoust
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544
| | - Guang Bian
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544
| | - Madhab Neupane
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544
| | - Daniel Sanchez
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544
| | - Hao Zheng
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan; Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, MA 02115
| | - Titus Neupert
- Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546; Department of Physics, National University of Singapore, Singapore 117542;
| | - M Zahid Hasan
- Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, NJ 08544;
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Hu J, Liu JY, Graf D, Radmanesh SMA, Adams DJ, Chuang A, Wang Y, Chiorescu I, Wei J, Spinu L, Mao ZQ. π Berry phase and Zeeman splitting of Weyl semimetal TaP. Sci Rep 2016; 6:18674. [PMID: 26726050 PMCID: PMC4698660 DOI: 10.1038/srep18674] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/23/2015] [Indexed: 11/28/2022] Open
Abstract
The recent breakthrough in the discovery of Weyl fermions in monopnictide semimetals provides opportunities to explore the exotic properties of relativistic fermions in condensed matter. The chiral anomaly-induced negative magnetoresistance and π Berry phase are two fundamental transport properties associated with the topological characteristics of Weyl semimetals. Since monopnictide semimetals are multiple-band systems, resolving clear Berry phase for each Fermi pocket remains a challenge. Here we report the determination of Berry phases of multiple Fermi pockets of Weyl semimetal TaP through high field quantum transport measurements. We show our TaP single crystal has the signatures of a Weyl state, including light effective quasiparticle masses, ultrahigh carrier mobility, as well as negative longitudinal magnetoresistance. Furthermore, we have generalized the Lifshitz-Kosevich formula for multiple-band Shubnikov-de Haas (SdH) oscillations and extracted the Berry phases of π for multiple Fermi pockets in TaP through the direct fits of the modified LK formula to the SdH oscillations. In high fields, we also probed signatures of Zeeman splitting, from which the Landé g-factor is extracted.
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Affiliation(s)
- J. Hu
- Department of physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - J. Y. Liu
- Department of physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - D. Graf
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - S. M. A. Radmanesh
- Advanced Materials Research Institute and Department of Physics, University of New Orleans, New Orleans, Louisiana 70148, USA
| | - D. J. Adams
- Advanced Materials Research Institute and Department of Physics, University of New Orleans, New Orleans, Louisiana 70148, USA
| | - A. Chuang
- Department of physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - Y. Wang
- Department of physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - I. Chiorescu
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - J. Wei
- Department of physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
| | - L. Spinu
- Advanced Materials Research Institute and Department of Physics, University of New Orleans, New Orleans, Louisiana 70148, USA
| | - Z. Q. Mao
- Department of physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118, USA
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Xu SY, Belopolski I, Sanchez DS, Zhang C, Chang G, Guo C, Bian G, Yuan Z, Lu H, Chang TR, Shibayev PP, Prokopovych ML, Alidoust N, Zheng H, Lee CC, Huang SM, Sankar R, Chou F, Hsu CH, Jeng HT, Bansil A, Neupert T, Strocov VN, Lin H, Jia S, Hasan MZ. Experimental discovery of a topological Weyl semimetal state in TaP. SCIENCE ADVANCES 2015; 1:e1501092. [PMID: 26702446 PMCID: PMC4681326 DOI: 10.1126/sciadv.1501092] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 09/20/2015] [Indexed: 05/26/2023]
Abstract
Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of Weyl fermions and exhibit protected Fermi arc surface states. However, they had been found to be extremely rare in nature. Recently, a family of compounds, consisting of tantalum arsenide, tantalum phosphide (TaP), niobium arsenide, and niobium phosphide, was predicted as a Weyl semimetal candidates. We experimentally realize a Weyl semimetal state in TaP. Using photoemission spectroscopy, we directly observe the Weyl fermion cones and nodes in the bulk, and the Fermi arcs on the surface. Moreover, we find that the surface states show an unexpectedly rich structure, including both topological Fermi arcs and several topologically trivial closed contours in the vicinity of the Weyl points, which provides a promising platform to study the interplay between topological and trivial surface states on a Weyl semimetal's surface. We directly demonstrate the bulk-boundary correspondence and establish the topologically nontrivial nature of the Weyl semimetal state in TaP, by resolving the net number of chiral edge modes on a closed path that encloses the Weyl node. This also provides, for the first time, an experimentally practical approach to demonstrating a bulk Weyl fermion from a surface state dispersion measured in photoemission.
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Affiliation(s)
- Su-Yang Xu
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Ilya Belopolski
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Daniel S. Sanchez
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Chenglong Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Cheng Guo
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Guang Bian
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Zhujun Yuan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Hong Lu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Pavel P. Shibayev
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | | | - Nasser Alidoust
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Hao Zheng
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
| | - Chi-Cheng Lee
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Shin-Ming Huang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Raman Sankar
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Fangcheng Chou
- Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
| | - Chuang-Han Hsu
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, MA 02115, USA
| | - Titus Neupert
- Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544, USA
| | - Vladimir N. Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore
| | - Shuang Jia
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - M. Zahid Hasan
- Laboratory for Topological Quantum Matter and Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ 08544, USA
- Princeton Center for Complex Materials, Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ 08544, USA
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73
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Du Y, Wan B, Wang D, Sheng L, Duan CG, Wan X. Dirac and Weyl Semimetal in XYBi (X = Ba, Eu; Y = Cu, Ag and Au). Sci Rep 2015; 5:14423. [PMID: 26399742 PMCID: PMC4585842 DOI: 10.1038/srep14423] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 08/28/2015] [Indexed: 11/29/2022] Open
Abstract
Weyl and Dirac semimetals recently stimulate intense research activities due to their novel properties. Combining first-principles calculations and effective model analysis, we predict that nonmagnetic compounds BaYBi (Y = Au, Ag and Cu) are Dirac semimetals. As for the magnetic compound EuYBi, although the time reversal symmetry is broken, their long-range magnetic ordering cannot split the Dirac point into pairs of Weyl points. However, we propose that partially substitute Eu ions by Ba ions will realize the Weyl semimetal.
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Affiliation(s)
- Yongping Du
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Bo Wan
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Di Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
| | - Li Sheng
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chun-Gang Duan
- Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062, China
| | - Xiangang Wan
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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