Z2 topology and edge states of twisted bilayer graphene

ORAL

Abstract

Recently twisted bilayer graphene (tBLG) emerges as a new platform of strongly correlated electrons near a magic twist angle, which hosts many exciting phenomena such as the Mott-like insulating phase, unconventional superconducting behavior, and emergent Chern ferromagnetism. Besides the apparent significance of band flatness, band topology may be another critical element responsible for the strongly correlated phenomena (like in the fractional quantum Hall effect) yet receives much less attention. We demonstrate that, while an unusual symmetry of tBLG trivializes the Berry curvature, two Z2 invariants characterize the topology of the moiré Dirac bands. We further show that subtle gapless edge states can survive in the electron and hole superlattice gaps of tBLG and mediate universal nonlocal transport that are robust to the interlayer electric field, twist angle, and edge termination.

*This theoretical work at UTD is supported by Army Research Office under Grant No. W911NF-18-1-0416 and Natural Science Foundation under Grant No. DMR-1921581 through the DMREF program.

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Presenters

  • Qiyue Wang

    • Department of Physics, University of Texas at Dallas
    • The Univerisity of Texas at Dallas

Authors

  • Chao Ma

    • Yale University
    • Department of Electrical Engineering, Yale University

  • Qiyue Wang

    • Department of Physics, University of Texas at Dallas
    • The Univerisity of Texas at Dallas

  • Scott Mills

    • Department of Physics, Stony Brook University
    • Stony Brook University

  • Xiaolong Chen

    • Yale University
    • Department of Electrical Engineering, Yale University

  • Bingchen Deng

    • Yale University
    • Department of Electrical Engineering, Yale University

  • Shaofan Yuan

    • Yale University
    • Department of Electrical Engineering, Yale University

  • Cheng Li

    • Yale University
    • Department of Electrical Engineering, Yale University

  • Kenji Watanabe

    • National Institute for Materials Science, Japan
    • National Institute for Material Science
    • National Institute for Materials Science
    • National Institute for Materials Science, Tsukuba
    • Research Center for Functional Materials, NIMS
    • nims
    • Advanced Materials Laboratory, National Institute for Materials Science
    • National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • NIMS
    • National Institute for Material Science - Japan
    • NIMS Tsukuba
    • National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan.
    • National Institute for Materials Science (NIMS)
    • National Institute for Materials Science,Tsukuba, Ibaraki 305-0047, Japan
    • Advanced Materials Laboratory, NIMS, Japan
    • National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan
    • National Institute of Materials Science
    • National Institute for Materials Science, University of Tsukuba
    • National Institute for Materials Science, Tsukuba, Japan
    • National Institute for Material Science, Japan
    • National Institue for Material Science, Tsukuba
    • Advanced Materials Laboratory, NIMS
    • Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba 305-0044, Japan
    • Advanced Matrials Lab, NIMS
    • National Institute for Material Science, Tsukuba, Japan
    • National institute for materials science
    • NIMS-Tsukuba
    • NIMS, Japan
    • National Institute for Materials Science, Namiki Tsukuba Ibaraki, Japan
    • NIRM
    • Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Japan
    • NIMS Japan
    • National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
    • Advanced Materials Laboratory, National Institute of Materials Science
    • Advanced Materials Laboratory, National Institute for Materials Science 1-1 Namiki, Tsukuba, 305-0044, Japan
    • National Institute of Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science (Japan)
    • Physics, NIMS
    • National Institute of Materials Science, Japan
    • National Institute of Materials Science (NIMS)
    • National Institute of Materials Science, Tsukuba, Ibaraki 305-0044, Japan
    • NIMS - Tsukuba

  • Takashi Taniguchi

    • National Institute for Materials Science, Japan
    • National Institute for Material Science
    • National Institute for Materials Science
    • National Institute for Materials Science, Tsukuba
    • Research Center for Functional Materials, NIMS
    • nims
    • Advanced Materials Laboratory, National Institute for Materials Science
    • National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • NIMS
    • National Institute for Material Science - Japan
    • NIMS Tsukuba
    • National Institute for Materials Science, Namiki 1-1, Ibaraki 305-0044, Japan.
    • National Institute for Materials Science (NIMS)
    • National Institute for Materials Science,Tsukuba, Ibaraki 305-0047, Japan
    • Advanced Materials Laboratory, NIMS, Japan
    • National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan
    • National Institute of Materials Science
    • National Institute for Materials Science, University of Tsukuba
    • National Institute for Materials Science, Tsukuba, Japan
    • National Institue for Material Science, Tsukuba
    • Advanced Materials Laboratory, NIMS
    • Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba 305-0044, Japan
    • Advanced Matrials Lab, NIMS
    • National Institute for Material Science, Tsukuba, Japan
    • National institute for materials science
    • NIMS-Tsukuba
    • NIMS, Japan
    • National Institute for Materials Science, Namiki Tsukuba Ibaraki, Japan
    • Advanced Materials Laboratory, National Institute for Materials Science, Tsukuba, Japan
    • NIMS Japan
    • National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan
    • Advanced Materials Laboratory, National Institute of Materials Science
    • Advanced Materials Laboratory, National Institute for Materials Science 1-1 Namiki, Tsukuba, 305-0044, Japan
    • National Institute of Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science (Japan)
    • Physics, NIMS
    • National Institute of Materials Science, Japan
    • National Institute of Materials Science, Tsukuba, Ibaraki 305-0044, Japan
    • NIMS - Tsukuba

  • Du Xu

    • State Univ of NY - Stony Brook
    • Department of Physics, Stony Brook University
    • Stony Brook University

  • Fan Zhang

    • University of Texas at Dallas
    • University of Texas, Dallas
    • Department of Physics, The University of Texas at Dallas
    • Department of Physics, University of Texas at Dallas
    • The University of Texas at Dallas
    • The Univerisity of Texas at Dallas

  • Fengnian Xia

    • Yale University
    • Department of Electrical Engineering, Yale University