Correlated Insulator Behaviour at Half-Filling in Magic Angle Graphene Superlattices

ORAL

Abstract

Twist angle between different layers of a van der Waals heterostructure plays a crucial role in the ultimate electronic properties. So far, the study of the effect of twist angles in vdW heterostructures has been mostly concentrated in graphene/hexagonal boron nitride (h-BN) twisted structures, which exhibit relatively weak interlayer interaction due to the presence of a large bandgap in h-BN. Here we show that when two graphene sheets are twisted by an angle close to the theoretically predicted 'magic angle', the resulting flat band structure near charge neutrality gives rise to a strongly-correlated electronic system. These flat bands exhibit half-filling insulating phases at zero magnetic field, which we show to be a Mott-like insulator arising from electrons localized in the moiré superlattice. These unique properties of magic-angle twisted bilayer graphene (TwBLG) open up a new playground for exotic many-body quantum phases in a 2D platform made of pure carbon and without magnetic field.

*This work has been primarily supported by the National Science Foundation (DMR-1405221) and Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF4541 for device fabrication, transport measurements, and data analysis.

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Presenters

  • Yuan Cao

    • Massachusetts Inst of Tech-MIT

Authors

  • Yuan Cao

    • Massachusetts Inst of Tech-MIT

  • Valla Fatemi

    • Massachusetts Inst of Tech-MIT
    • Massachusetts Institute of Technology

  • Ahmet Demir

    • Massachusetts Inst of Tech-MIT
    • Physics, Massachusetts Inst of Tech-MIT

  • Shiang Fang

    • Department of Physics, Harvard University
    • Harvard University

  • Spencer Tomarken

    • Massachusetts Inst of Tech-MIT

  • Jason Luo

    • Massachusetts Inst of Tech-MIT

  • Javier Sanchez-Yamagishi

    • Department of Physics, Harvard University

  • Kenji Watanabe

    • National Institute for Materials Science
    • NIMS
    • National Institute for Material Science
    • Advanced Materials Laboratory, National Institute for Materials Science
    • National Institute of Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science
    • National Institute for Materials Science (NIMS
    • Advanced Materials Laboratory, NIMS
    • National Institute for Materials Science, Advanced Materials Laboratory
    • National Institue for Materials Science
    • National Institute of Material Science
    • National Institute for Matericals Science
    • Advanced Materials Laboratory
    • National Institute for Materials Science, 1-1 Namiki
    • Advanced materials laboratory, National institute for Materials Science
    • NIMS-Japan

  • Takashi Taniguchi

    • National Institute for Materials Science
    • NIMS
    • National Institute for Material Science
    • Advanced Materials Laboratory, National Institute for Materials Science
    • National Institute of Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science
    • National Institute for Materials Science (NIMS
    • Advanced Materials Laboratory, NIMS
    • National Institute for Materials Science, Advanced Materials Laboratory
    • National Institue for Materials Science
    • National Institute of Material Science
    • National Institute for Matericals Science
    • Advanced Materials Laboratory
    • National Institute for Materials Science, 1-1 Namiki
    • NIMS-Japan

  • Efthimios Kaxiras

    • Department of Physics, Harvard University
    • Harvard Univ
    • Harvard University
    • Physics, Harvard University
    • School of Engineering and Applied Science, Harvard University

  • Raymond Ashoori

    • Massachusetts Inst of Tech-MIT
    • Physics, Massachusetts Inst of Tech-MIT

  • Pablo Jarillo-Herrero

    • Massachusetts Inst of Tech-MIT
    • Department of Physics, Massachusetts Institute of Technology
    • Physics, MIT
    • MIT
    • Massachusetts Institute of Technology