Direct Imaging of Magnetic Structure in Twisted Bilayer Graphene with Scanning nanoSQUID-On-Tip Microscopy

ORAL

Abstract

Bilayer graphene, rotationally faulted to ~1.1 degree misalignment, has recently been shown to host superconducting and resistive states associated with the formation of a flat electronic band. While numerous theories exist for the origins of both states, direct validation of these theories remains an outstanding experimental problem. Here, we focus on the resistive states occurring at commensurate filling (1/2, 1/4, and 3/4) of the two lowest superlattice bands. We test theoretical proposals that these states arise due to broken spin—and/or valley—symmetry by performing direct magnetic imaging with nanoscale SQUID-on-tip microscopy. This technique provides single-spin resolved magnetometry on sub-100nm length scales. I will present imaging data from our 4.2K nSOT microscope on graphite-gated twisted bilayers near the flat band condition and discuss the implications for the physics of the commensurate resistive states.

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Presenters

  • Marec Serlin

    University of California, Santa Barbara

Authors

  • Marec Serlin

    University of California, Santa Barbara

  • Charles Tschirhart

    University of California, Santa Barbara

  • Hryhoriy Polshyn

    University of California, Santa Barbara, Department of Physics, University of California, Santa Barbara, CA 93106, USA

  • Jiacheng Zhu

    University of California, Santa Barbara

  • Martin E Huber

    Physics, University of Colorado, Denver, University of Colorado, Denver

  • Andrea Young

    University of California, Santa Barbara, Department of Physics, University of California, Santa Barbara, CA 93106, USA