Local spectroscopic study of moiré band flattening and correlated gaps in magic-angle twisted bilayer graphene

ORAL

Abstract

Magic angle (~1.1°) twisted bilayer graphene (TBG) shows a wide range of correlated electronic states that originate from the flat moiré bands. Scanning tunneling spectroscopy experiments on TBG near the magic angle observed, a large separation between van Hove singularities and finite Dirac velocities signaling relatively large bandwidth that is not compatible with the continuum model expectations. While these previous measurements highlight the presence of electronic interactions, their impact on the band structure is still unclear. Here, we report scanning tunneling spectroscopy measurements of TBG across the area where the twist angle slowly changes from non-magic to magic-angle value. By systematically following the evolution of the moiré electronic bands, we study doping dependent band deformations. Surprisingly, we discover interaction-driven band flattening that can be also related to gap opening near half-filling. Our results provide crucial insights into the robustness of half-filling correlated phases.

*This work is supported by NSF through grants DMR 2005129 and DMR-1723367 and by the Army Research Office under Grant Award W911NF-17-1-0323. H. K. was supported by Kwanjeong Educational Foundation. We also acknowledge support by IQIM, NSF funded physics frontiers center.

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Presenters

  • Hyunjin Kim

    • Caltech
    • Department of Physics, California Institute of Technology

Authors

  • Hyunjin Kim

    • Caltech
    • Department of Physics, California Institute of Technology

  • Youngjoon Choi

    • Caltech
    • Department of Physics, California Institute of Technology

  • Cyprian Lewandowski

    • Department of Physics, California Institute of Technology
    • California Institute of Technology
    • Caltech

  • Yang Peng

    • Department of Physics and Astronomy, California State University, Northridge, USA
    • Caltech
    • California State University, Northridge

  • Alex R Thomson

    • Caltech
    • Department of Physics, California Institute of Technology

  • Kenji Watanabe

    • National Institute for Materials Science
    • National Institute for Materials Science, Japan
    • National Institure for Materials Science
    • Advanced Materials Laboratory, National Institute for Materials Science
    • NIMS
    • National Institute of Materials Science
    • National Institute for Materials Science (NIMS)
    • Research Center for Functional Materials, National Institute for Materials Science
    • National Institute for Materials Science,1-1 Namiki
    • National Institute of Material Science
    • National Institute for Materials Science, Tsukuba, Japan
    • Research Center for Functional Materials, NIMS
    • National Institute of Materials Science, Tsukuba, Japan
    • National Institude for Materials Science
    • National Institute for Materials Science, Tsukuba, Ibaraki, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
    • International Center for Materials Nanoarchitectonics, National Institute for Materials
    • NIMS - Japan
    • National Institute for Materials Science ,Japan
    • National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan
    • National Institute for Material Science
    • National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science Japan
    • NIMS Tsukuba
    • National Institute for Materials Science, Research Center for Functional Materials, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Materials Science: Namiki, Tsukuba, Ibaraki, JP
    • National Institue for Material Science
    • National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan
    • Materials, NIMS
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, National In
    • Research Center for Functional Materials, Japan
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • International Center for Materials nanoarchtectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
    • NIMS Suguba
    • NIMS, Tsukuba, Japan
    • National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Ibaraki, Japan
    • National institute of material science
    • Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
    • Advanced Materials Laboratory, NIMS
    • Research Center for Functional Materials, National Institute for Materials Science, Ibaraki, Japan
    • National Institute for Materials Science, Research Center for Functional Materials
    • National Institute of Material Science, Japan
    • Tsukuba, National Institute for Materials Science

  • Takashi Taniguchi

    • National Institute for Materials Science
    • National Institute for Materials Science, Japan
    • National Institure for Materials Science
    • Advanced Materials Laboratory, National Institute for Materials Science
    • NIMS
    • National Institute of Materials Science
    • National Institute for Materials Science (NIMS)
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • National Institute for Materials Science,1-1 Namiki
    • National Institute of Material Science
    • National Institute for Materials Science, Tsukuba, Japan
    • International Center for Materials Nanoarchitectonics, NIMS
    • Research Center for Functional Materials, National Institute for Materials Science
    • National Institute of Materials Science, Tsukuba, Japan
    • National Institude for Materials Science
    • International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan
    • International Center for Materials Nanoarchitectonics, National Institute for Materials
    • NIMS - Japan
    • National Institute for Materials Science ,Japan
    • National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan
    • National Institute for Material Science
    • National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan
    • National Institute for Material Science Japan
    • 8International Center for Materials Nanoarchitectonics
    • NIMS Tsukuba
    • National Institute for Materials Science: Namiki, Tsukuba, Ibaraki, JP
    • National Institue for Material Science
    • National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, National In
    • Research Center for Functional Materials, Japan
    • Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
    • International Center for Material Nanoarchitectonics, National Institute for Materials Science
    • International Center for Materials Nanoarchitectonics
    • NIMS Suguba
    • NIMS, Tsukuba, Japan
    • National Cheng Kung University
    • National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Ibaraki, Japan
    • National institute of material science
    • Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
    • Advanced Materials Laboratory, NIMS
    • National Institute for Materials Science, International Center for Materials Nanoarchitectonics
    • National Institute of Material Science, Japan
    • Tsukuba, National Institute for Materials Science

  • Jason F. Alicea

    • Caltech
    • Department of Physics, California Institute of Technology
    • Department of Physics and Institute for Quantum Information and Matter; Walter Burke Institute for Theoretical Physics, California Institute of Technology

  • Stevan Nadj-Perge

    • Caltech
    • Watson Laboratory of Applied Physics, California Institute of Technology
    • Physics, California Institute of Technology