Coexistence of Dirac and Weyl points in hexagonal <i>ABC</i> crystals

ORAL

Abstract

We propose that the noncentrosymmetric hexagonal ABC crystal SrHgPb realizes a new type of topological semimetal that hosts both Dirac and Weyl points in momentum space. Six pairs of Weyl points and one pair of Dirac points coexist in the Brillouin zone. All twelve Weyl points are located in the kz = 0 plane at about 0.25 eV above the Fermi energy and are related by the C6v point group symmetry. The existence of the Weyl points is confirmed by calculations of the Berry flux and the surface Fermi arcs. The Dirac points, which can be considered as double Weyl points with zero Chern number, occur along the C6z rotational axis and are protected by C6v point group symmetry. The Dirac points in the z axis are about 0.11 eV below the Fermi energy and form two electron pockets. We study topological phase transitions as a function of the HgPb buckling in SrHgPb and other material realizations of related topological semimetals that occur in the family of hexagonal ABC crystals. Our finding should provide a realistic and promising platform for studying the interplay between Dirac points and Weyl points, and for understanding their effects on transport and optical properties.

*National Key Basic Research Program of China (Grant No. 2015CB921600)

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Presenters

  • Heng Gao

    • Department of Physics, Shanghai University

Authors

  • Heng Gao

    • Department of Physics, Shanghai University

  • Youngkuk Kim

    • Sungkyunkwan University
    • Physics, Sungkyunkwan University
    • Department of Physics, Sungkyunkwan University(SKKU)
    • Department of Chemistry, University of Pennsylvania
    • Physics, Sungkyunkwan Univ

  • J.W.F. Venderbos

    • Massachusetts Inst of Tech-MIT
    • Physics, University of Pennsylvania
    • Chemistry, University of Pennsylvania
    • Department of Chemistry, University of Pennsylvania

  • Charles Kane

    • Univ of Pennsylvania
    • Department of Physics and Astronomy, University of Pennsylvania
    • Physics, University of Pennsylvania

  • Eugene Mele

    • Physics & Astronomy, University of Pennsylvania
    • Physics and Astronomy, University of Pennsylvania
    • Department of Physics and Astronomy, University of Pennsylvania
    • Univ of Pennsylvania
    • University of Pennsylvania

  • Andrew Rappe

    • Univ of Pennsylvania
    • Chemistry, University of Pennsylvania
    • Chemistry, Univ of Pennsylvania
    • Department of Chemistry, University of Pennsylvania

  • Wei Ren

    • Shanghai Univ
    • Physics, Shanghai University
    • Department of Physics, Shanghai University
    • Department of Physics, International Center of Quantum and Molecular Structures, and Materials Genome Institute, Shanghai University
    • Shanghai University