Strong Correlations in Magic Angle Twisted Bilayer Graphene Investigated by Scanning Tunneling Microscopy

ORAL

Abstract

Recent results on twisted bilayer graphene near the “magic” angle of 1.1 degrees reveal gate-tunable superconducting and correlated insulating states generally attributed to the flat band emerging from the moire superlattice and hybridization between the two layers. To date, the investigation of these states has been limited to bulk probes, inherently hindered by overall sample disorder and inhomogeneity. Using gated scanning tunneling microscopy and spectroscopy (STS), we directly locally investigate twisted bilayer graphene around the magic angle. Many theories have been proposed as to the precise band structure which causes the insulating and superconducting states to emerge, but the question remains for instance as to the size of the gap at charge neutrality and at half filling of the moire superlattices. We show the real experimental L-DOS probed by STS at and near the magic angle with gate tunable doping. Our results show the size of the gap at charge neutrality as well as the half filling state which enables a better understanding of the correlation effects leading to the insulating and superconducting states. Additionally, we study the effects of the local inhomogeneity which likely leads to the variable results observed in transport.

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Presenters

  • Alexander Kerelsky

    • Physics Department, Columbia University

Authors

  • Alexander Kerelsky

    • Physics Department, Columbia University

  • Leo McGilly

    • Physics Department, Columbia University
    • Columbia University

  • Shaowen Chen

    • Department of Physics, Columbia University
    • Columbia University
    • Applied Physics and Math Department, Columbia University

  • Matthew Yankowitz

    • Columbia University
    • Department of Physics, Columbia University
    • Physics Department, Columbia University

  • Lede Xian

    • Max Planck Institute for the Structure and Dynamics of Matter

  • Dante Kennes

    • Freie Universitaet Berlin
    • Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universitat Berlin
    • Max Planck Institute for the Structure and Dynamics of Matter
    • Freie Universität Berlin
    • Physics, Freie Universität Berlin
    • Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin
    • Fachbereich Physik, Freie Universit{\"a}t Berlin
    • Columbia University

  • Angel Rubio

    • Max Planck Institute for the Structure and Dynamics of Matter
    • Max Planck Institute for the Structure and Dynamics of Matter and Center for Free-Electron Laser Science
    • Max-Planck Institute for the structure and dynamics of matter
    • Max Planck Inst Structure & Dynamics of Matter
    • Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany
    • Universidad del País Vasco UPV/EHU and Max Planck Institute for the Structure and Dynamics of Matter
    • Theory, Max Planck Institute for the Structure and Dynamics of Matter (MPSD)

  • Cory R Dean

    • Columbia University
    • Department of Physics, Columbia University in the City of New York
    • Department of Physics, Columbia University
    • Physics, Columbia University
    • Physics Department, Columbia University

  • Abhay Pasupathy

    • Columbia University
    • Physics, Columbia University
    • Department of Physics, Columbia University in the City of New York
    • Physics Department, Columbia University
    • Department of Physics, Columbia University