A Quantum Ruler for Topology and Quantum Geometry in Moiré Superlattices: Part 3/3

ORAL

Abstract

Flat and narrow band physics in moiré quantum matter (MQM) has proven to be extremely rich with new emergent quantum phases. The topological properties of the eigenstates of the moiré Hamiltonian are critical for establishing the quantum phase of the system. While the emergence of non-trivial Chern numbers has been observed, it is important to characterize the quantum geometry in detail including Berry curvature and less known quantum metric effects throughout the bands. Using a local probe, we employ magnetic oscillations as a “ruler” for quantum geometry in small-angle twisted double bilayer graphene (TDBG). Part 3: The experimentally observed magnetic response in TDBG deviates strongly from the semiclassical Onsager relation. We use the expanded Onsager relation to capture the quantum geometric effects. The first-order correction in B, interpreted as orbital magnetic moment, manifests as valley splitting of Landau levels. The second-order correction—orbital magnetic susceptibility—is anomalously large and exceeds the first order for certain displacement fields. We show that this breakdown of the original Onsager relation is unique to the superlattice constants typical for MQM.

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Publication: M. R. Slot, Y. Maximenko, P. M. Haney, S. Kim, D. T. Walkup, E. Strelcov, E. M. Shih, D. Yildiz, S. T. Le, S. R. Blankenship, K. Watanabe, T. Taniguchi, Y. Barlas, N. B. Zhitenev, F. Ghahari and J. A. Stroscio, A Quantum Ruler for Topology and Quantum Geometry in Moiré Superlattices, submitted

Presenters

  • Marlou R Slot

    • National Institute of Standards and Technology

Authors

  • Marlou R Slot

    • National Institute of Standards and Technology

  • Yulia Maximenko

    • National Institute of Standards and Technology
    • National Institute of Standards and Tech

  • Paul Haney

    • National Institute of Standards and Technology

  • Sungmin Kim

    • National Institute of Standards and Technology

  • Daniel T Walkup

    • National Institute of Standards and Technology

  • En-Min Shih

    • National Institute of Standards and Technology
    • National Institute of Standards and Tech

  • Dilek Yildiz

    • NIST / JQI - Physics department UMD
    • Harvard 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

  • Yafis Barlas

    • University of Nevada, Reno

  • Nikolai Zhitenev

    • National Institute of Standards and Technology

  • Fereshte Ghahari Kermani

    • National Institute of Standards and Technology

  • Joseph A Stroscio

    • National Institute of Standards and Technology
    • National Institute of Standards and Tech