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$Z_2$ Topology and Edge States of Twisted Bilayer Graphene

ORAL

Abstract

Recently twisted bilayer graphene(t-BLG) emerges as a new strongly correlated physical platform near a magic twist angle, which hosts many exciting phenomena such as the Mott-like insulating phases, unconventional superconducting behavior and emergent ferromagnetism. Besides the apparent significance of band flatness, band topology may be another critical element in strongly correlated twistronics yet receives much less attention. While an unusual symmetry of t-BLG trivializes Berry curvature, we elucidate that two high-dimensional $Z_2$ invariants in the Teo-Kane Altland-Zirnbauer table characterize the topology of the moir\'{e} Dirac bands, supported by a systematic nonlocal transport study. The moir\'{e} band topology of t-BLG manifests itself as two pronounced nonlocal responses in the electron and hole superlattice gaps. Moreover, the nonlocal responses are robust to the interlayer electric field, twist angle, and edge termination, exhibiting a universal scaling law.

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Authors

  • Qiyue Wang

    Department of Physics, University of Texas at Dallas

  • Chao Ma

    University of Texas at Arlington, Florida International University, Texas A&M University-Commerce, Texas A&M University–Commerce, University of Houston Downtown, Texas A\&M University, Carnegie Mellon University, Department of Physics, MSEC, Texas State University, Ingram School of Engineering, MSEC, Texas State University, MSEC, Texas State University, Ingram School of Engineering, Texas State University, Department of Chemistry and Biochemistry, North Carolina Central University, Durham, NC 27707, USA, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA, Texas Tech University, Texas A&M University, University of San Francisco, University of Wuppertal, University of Illinois at Urbana-Champaign, University of Houston, University of Texas at Dallas, Mitchell Institute for Fundamental Physics and Astronomy, Texas A & M University, Center for Neutrino Physics, Department of Physics Virginia Tech, None, Department of Physics, University of Texas at Dallas, Department of Electrical Engineering, Yale University

  • Chao Ma

    University of Texas at Arlington, Florida International University, Texas A&M University-Commerce, Texas A&M University–Commerce, University of Houston Downtown, Texas A\&M University, Carnegie Mellon University, Department of Physics, MSEC, Texas State University, Ingram School of Engineering, MSEC, Texas State University, MSEC, Texas State University, Ingram School of Engineering, Texas State University, Department of Chemistry and Biochemistry, North Carolina Central University, Durham, NC 27707, USA, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA, Texas Tech University, Texas A&M University, University of San Francisco, University of Wuppertal, University of Illinois at Urbana-Champaign, University of Houston, University of Texas at Dallas, Mitchell Institute for Fundamental Physics and Astronomy, Texas A & M University, Center for Neutrino Physics, Department of Physics Virginia Tech, None, Department of Physics, University of Texas at Dallas, Department of Electrical Engineering, Yale University

  • Chao Ma

    University of Texas at Arlington, Florida International University, Texas A&M University-Commerce, Texas A&M University–Commerce, University of Houston Downtown, Texas A\&M University, Carnegie Mellon University, Department of Physics, MSEC, Texas State University, Ingram School of Engineering, MSEC, Texas State University, MSEC, Texas State University, Ingram School of Engineering, Texas State University, Department of Chemistry and Biochemistry, North Carolina Central University, Durham, NC 27707, USA, Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802, USA, Texas Tech University, Texas A&M University, University of San Francisco, University of Wuppertal, University of Illinois at Urbana-Champaign, University of Houston, University of Texas at Dallas, Mitchell Institute for Fundamental Physics and Astronomy, Texas A & M University, Center for Neutrino Physics, Department of Physics Virginia Tech, None, Department of Physics, University of Texas at Dallas, Department of Electrical Engineering, Yale University