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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