Negative magnetoresistance in large-angle twisted bilayer graphene

ORAL

Abstract

Twisting two sheets of graphene can lead to a stunning array of new electronic properties. Most famously, twisted bilayer graphene (tBLG) at the magic angle of 1.1° exhibits superconductivity, orbital magnetism, and topological insulating states. At larger twist angles, the Dirac cones from the two graphene sheets become electronically decoupled owing to their large separation in momentum space. Large-angle tBLG therefore behaves approximately like monolayer graphene, but with an extra two-fold layer degeneracy that can be lifted by a perpendicular electric field. Here, we report the surprising observation of negative magnetoresistance (NMR) in such samples. We observe ubiquitous NMR when the two graphene layers are doped to the same carrier type, as well as at the charge neutrality point in the special case of zero displacement field. In the doped case, the NMR persists above room temperature. These observations contrast the typical transport properties of ultra-clean monolayer or Bernal bilayer graphene, necessitating a new theoretical framework for understanding their origin.

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Presenters

  • Xuetao Ma

    • University of Washington

Authors

  • Xuetao Ma

    • University of Washington

  • Zhaoyu Liu

    • University of Washington

  • Kenji Watanabe

    • National Institute for Materials Science
    • NIMS
    • Research Center for Electronic and Optical Materials, National Institute for Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science

  • Takashi Taniguchi

    • Kyoto Univ
    • National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • National Institute for Materials Sciences
    • NIMS
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science
    • International Center for Materials Nanoarchitectonics, NIMS, Japan
    • International Center for Materials Nanoarchitectonics, Tsukuba
    • National Institue for Materials Science
    • Kyoto University
    • National Institute of Materials Science
    • International Center for Materials Nanoarchitectonics and National Institute for Materials Science

  • David H Cobden

    • University of Washington

  • Jiun-Haw Chu

    • University of Washington
    • Department of Physics, University of Washington, Seattle, WA 98105

  • Matthew Yankowitz

    • University of Washington