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Topology on a new facet of bismuth

ORAL

Abstract

Bismuth-based materials have been instrumental in the development of topological physics, even though bulk bismuth itself has been long thought to be topologically trivial. A recent study has, however, shown that bismuth is in fact a higher-order topological insulator featuring one-dimensional (1D) topological hinge states protected by three-fold rotational and inversion symmetries. In this talk, we uncover another hidden facet of the band topology of bismuth by showing that bismuth is also a first-order topological crystalline insulator protected by a two-fold rotational symmetry. As a result, its $(1\bar{1}0)$ surface exhibits a pair of gapless Dirac surface states. Remarkably, these surface Dirac cones are unpinned in the sense that they are not restricted to locate at specific $k$ points in the $(1\bar{1}0)$ surface Brillouin zone. These unpinned 2D Dirac surface states could be probed directly via various spectroscopic techniques. Our analysis also reveals the presence of a distinct, previously uncharacterized set of 1D topological hinge states protected by the two-fold rotational symmetry. Our study thus provides a comprehensive understanding of the topological band structure of bismuth.

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Presenters

  • Hsin Lin

    Academia Sinica, Physics, Academia Sinica, Institute of Physics, Academia Sinica, Taipei, Taiwan, Institute of Physics, Academia Sinica

Authors

  • Hsin Lin

    Academia Sinica, Physics, Academia Sinica, Institute of Physics, Academia Sinica, Taipei, Taiwan, Institute of Physics, Academia Sinica

  • Chuang-Han Hsu

    National University of Singapore

  • XIAOTING ZHOU

    National Cheng Kung University, Physics and Astronomy, California State University, Northridge, Department of Physics and Astronomy, California State University, Northridge

  • Tay-Rong Chang

    National Cheng Kung University, Physics, National Cheng Kung University, Department of Physics, National Cheng Kung University, National Cheng Kung University, Taiwan

  • Qiong Ma

    Massachusetts Institute of Technology, Massachusetts Institute of Technology MIT

  • Nuh Gedik

    Massachusetts Institute of Technology MIT, Massachusetts Institute of Technology, Physics, MIT

  • Arun Bansil

    Northeastern University, Physics, Northeastern University

  • Suyang Xu

    Massachusetts Institute of Technology, Massachusetts Institute of Technology MIT, Physics, Massachusetts Institute of Technology, Harvard university, Harvard University, Havard University

  • Liang Fu

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