Unusual magnetotransport in twisted bilayer graphene from strain-induced open Fermi surfaces

ORAL

Abstract

Uniaxial heterostrain in twisted bilayer graphene can have a profound effect on the bandstructure. In this talk, we will discuss the effects of strain in a twisted bilayer graphene device with a twist angle slightly above the magic angle as seen in both theory and transport. Features such as a non-saturating magnetoresistance are well described by our addition of uniaxial heterostrain into the Bistritzer-MacDonald model. We find that strain breaks the degeneracy of the three van Hove points, leading to broad range of densities where open Fermi surfaces exists, explaining the non-saturating magnetoresistance. Additionally, our theory also predicts a marked rotation of the electrical transport principal axes as a function of filling even for fixed strain and for rigid bands. Our results indicate that strain-induced effects may lead to similar phenomenology as interaction-induced nematic order.

*X.W. acknowledges financial support from National MagLab through Dirac fellowship, which is funded by the National Science Foundation (Grant No. DMR-1644779) and the state of Florida. O.V. was supported by NSF Grant No. DMR-1916958 and is partially funded by the Gordon and Betty Moore Foundation’s EPiQS Initiative Grant GBMF11070, National High Magnetic Field Laboratory through NSF Grant No. DMR-1157490 and the State of Florida. Device measurements and analysis were supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under contract DE-AC02-76SF00515. Measurement infrastructure was funded in part by the Gordonand Betty Moore Foundation’s EPiQS Initiative through grant GBMF3429 and grant GBMF9460. D.G.-G. gratefully acknowledges support from the Ross M. Brown Family Foundation. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DENA0003525. K.W. and T.T. acknowledge support fromJSPS KAKENHI (Grant Numbers 19H05790, 20H00354 and 21H05233). Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award ECCS 2026822

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Publication: https://arxiv.org/abs/2209.08204

Presenters

  • Aaron L Sharpe

    • Sandia National Laboratories

Authors

  • Aaron L Sharpe

    • Sandia National Laboratories

  • Xiaoyu Wang

    • National High Magnetic Field Laboratory

  • Joe Finney

    • Stanford Univ

  • Linsey Rodenbach

    • Stanford Univ

  • Connie L Hsueh

    • Stanford University

  • Kenji Watanabe

    • National Institute for Materials Science
    • Research Center for Functional Materials, National Institute of Materials Science
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan
    • NIMS
    • Research Center for Functional Materials, National Institute for Materials Science
    • National Institute for Materials Science, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
    • NIMS Japan

  • Takashi Taniguchi

    • National Institute for Materials Science
    • Kyoto Univ
    • International Center for Materials Nanoarchitectonics, National Institute of Materials Science
    • Kyoto University
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-044, Japan
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • National Institute for Materials Science, Japan
    • National Institute For Materials Science
    • NIMS
    • National Institute for Material Science
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
    • NIMS Japan

  • Marc A Kastner

    • Stanford Univ

  • Oskar Vafek

    • Florida State University

  • David Goldhaber-Gordon

    • Stanford Univ
    • Stanford University

  • David Goldhaber-Gordon

    • Stanford Univ
    • Stanford University