Superconductivity and Ferroelectric Orbital Magnetism in Semimetallic Rhombohedral Hexalayer Graphene

ORAL

Abstract

Rhombohedral multilayer graphene has emerged as a promising platform for exploring correlated and topological quantum phases, enabled by its Berry-curvature-bearing flat bands. While prior work has focused on separated conduction and valence bands, we probe the extensive semimetallic regime of rhombohedral hexalayer graphene. We survey a rich phase diagram dominated by flavor-symmetry breaking and reveal an electric-field-driven band inversion through fermiology. Near this inversion, we find a superconducting-like state confined to a region with emergent electron and hole Fermi surfaces. In addition, two multiferroic orbital-magnetic phases are observed: a ferrovalley state near zero field and a ferroelectric state at large fields around charge neutrality. The latter shows electric-field-reversible magnetic hysteresis, consistent with a ΔP·M multiferroic order parameter.

*X. L. acknowledges support from the National Science Foundation through the CAREER program under Award No. DMR-2442363. J. D. acknowledges support from the New Frontier Grant, College of Arts & Sciences, Cornell University. The device fabrication is performed in part in Cornell Center for Materials Research and in part at the Cornell NanoScale Facility, a member of the National Nanotechnology Coordinated Infrastructure (NNCI), which is supported by the National Science Foundation (Grant NNCI-2025233). K.W. and T.T. acknowledge support from the JSPS KAKENHI (Grant Numbers 21H05233 and 23H02052), the CREST (JPMJCR24A5), JST and World Premier International Research Center Initiative (WPI), MEXT, Japan.

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Publication: arXiv:2508.15909

Presenters

  • Jinghao Deng

    • Lab of Atomic and Solid State Physics, Cornell
    • Lab of Atomic and Solid State Physics, Cornell University

Authors

  • Jinghao Deng

    • Lab of Atomic and Solid State Physics, Cornell
    • Lab of Atomic and Solid State Physics, Cornell University

  • Jiabin Xie

    • Lab of Atomic and Solid State Physics, Cornell
    • Cornell University

  • Hongyuan Li

    • Lab of Atomic and Solid State Physics, Cornell
    • Cornell University

  • Takashi Taniguchi

    • National Institute for Materials Science
    • Research Center for Materials Nanoarchitectonics, National Institute for Materials Science
    • International Center for Materials Nanoarchitectonics, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan
    • Research Center for Functional Materials, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan

  • Kenji Watanabe

    • National Institute for Materials Science
    • Research Center for Functional Materials, National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan

  • Jie Shan

    • Cornell University

  • Kin Fai Mak

    • Cornell University

  • Xiaomeng Liu

    • Cornell University