Electronic structure of topological nodal semimetals

Invited

Abstract

Topological phases in condensed matter physics have attracted intense worldwide interest in the past decade because these phases lie outside the framework of Landau’s spontaneous symmetry breaking paradigm. The early period of the field explored topological insulators (TIs). Three-dimensional (3D) TIs are distinct from the conventional band insulators in that they feature a bulk energy gap driven by spin-orbit coupling effects, and gapless surface states protected by time-reversal symmetry. In the last few years, the focus has shifted from insulators to topological semimetals (TSMs). Three types of TSMs have been identified, namely, Dirac, Weyl, and nodal-line semimetals. Dirac and Weyl semimetals are 3D analogs of graphene in which the bulk band structure disperses linearly from the nodal point in all three momentum directions, while the nodal-line semimetals display 1D nodal loops in the 3D Brillouin zone. In addition to the graphene-type (type-I) TSMs, the novel type-II TSMs where the band dispersion strongly violates Lorentz symmetry have also been studied extensively. In this talk, we will review a range of materials predictions including type-II Dirac semimetals [1], tunable Weyl semimetals [2], and nodal-line semimetals [3-5] by using first-principles calculations, and discuss various exotic phenomena observed experimentally in these compounds.

[1] T.-R. Chang et al, Phys. Rev. Lett. 119, 026404 (2017).
[2] T.-R. Chang et al, Nat. Commun. 7, 10639 (2016).
[3] G. Bian et al, Nat. Commun. 7, 10556 (2016).
[4] G. Bian et al, Phys. Rev. B 93,121113(R) (2016).
[5] T.-R. Chang et al, arXiv:1711.09167 (2017).

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Presenters

  • Tay-Rong Chang

    National Cheng Kung University, Physics, National Cheng Chung University, Physics, National Cheng Kung University, Tainan, 701, Taiwan, Department of Physics, National Cheng Kung University, Physics, National Tsing Hua University, Physics, National Cheng Kung University

Authors

  • Tay-Rong Chang

    National Cheng Kung University, Physics, National Cheng Chung University, Physics, National Cheng Kung University, Tainan, 701, Taiwan, Department of Physics, National Cheng Kung University, Physics, National Tsing Hua University, Physics, National Cheng Kung University

  • Guang Bian

    Physics, University of Missouri, University of Missouri, Physics, U. of Missouri

  • Suyang Xu

    Department of Physics, Massachusetts Institute of Technology, Massachusetts Institute of Technology, MIT, Physics, MIT, Department of Physics, Massachusetts Institute of Technology, Cambridge

  • Guoqing Chang

    Department of Physics, Princeton University, Princeton University, Physics, Princeton U.

  • Arun Bansil

    Department of Physics, Northeastern University, Northeastern, Physics, Northeastern University, Boston, Massachusetts 02115, USA, Northeastern University, Northeastern University, Boston (MA), USA, Physics, Northeastern U., Department of Physics, Northwestern University, Physics, Northeastern University, Boston, MA, USA

  • Robert Cava

    Department of Chemistry, Princeton University, Princeton University, Chemistry, Princeton U., Chemistry, Princeton University

  • Hsin Lin

    Academia Sinica, Institute of Physics, Academia Sinica, Physics, Academia Sinica, Taipei 11529, Taiwan, Institute of Physics, Academia Sinica, Taipei 11529, Taiwan, Physics, Academia Sinica, Department of Physics, National University of Singapore, National University of Singapore, Academia Sinica, Taipei, Taiwan

  • Zahid Hasan

    Department of Physics, Princeton University, Princeton University, Laboratory for Topological Quantum Matter & Advanced Spectroscopy, Princeton University, Physics, Princeton U.