Fractional Chern Insulators and Hofstadter Band Geometry in Magic-Angle Graphene

ORAL

Abstract

Fractional Chern Insulators (FCIs) generalize the celebrated fractional quantum hall effect to the lattice setting. A number of theoretical proposals have suggested (hBN-aligned) magic-angle graphene (MATBG) is a prime candidate for realizing FCIs, as its bandstructure and quantum geometry are relatively close to that of the lowest Landau level. Indeed, this was borne out in a recent experiment, which observed 8 FCIs in hBN-MATBG at magnetic fields as low as 5 Tesla. This talk will examine a constellation of questions surrounding this experiment. Can we understand the appearance of these FCIs? What quantum geometric conditions are necessary to favor FCIs in the minibands of the Hofstadter butterfly? Can MATBG support FCIs without an external field?

*This research is funded in part by the Gordon and Betty Moore Foundation's EPiQS Initiative, Grant GBMF8683 to D.E.P.

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Publication: Fractional Chern Insulators and Hofstadter Band Geometry in Magic-Angle Graphene, in preparation.
See also: Fractional Chern insulators in magic-angle twisted bilayer graphene, arXiv: 2107.10854

Presenters

  • Daniel E Parker

    • University of California, Berkeley
    • Harvard University

Authors

  • Daniel E Parker

    • University of California, Berkeley
    • Harvard University

  • Patrick J Ledwith

    • Harvard University

  • Eslam Khalaf

    • Harvard University

  • Tomohiro Soejima

    • University of California, Berkeley

  • Johannes Hauschild

    • University of California, Berkeley

  • Ashvin Vishwanath

    • Harvard University