The three fractional quantum Hall states at filling factor ν = 7/5 in bilayer graphene

ORAL

Abstract

The celebrated fractional quantum Hall (FQH) effect takes on new twists in Bernal-stacked bilayer graphene due to its orbital and valley degrees of freedom. In our previous work, we made ultra-high-quality dual-gated devices and observed a new even-denominator state at ν = 5/2 and demonstrated the ability to select the orbital wave function (N=0 vs N=1) for a given Landau level (LL) using a perpendicular electric displacement field D (Huang et al., Phys. Rev. X 12, 031019 (2022)). In this talk, we examine the phase diagram of filling factor ν = 7/5 in a wide range of displacement and magnetic fields. Three FQH states are found. The 7/5 state riding on the N=0 LL exhibits the familiar properties of Jain FQH states. The state riding on the N=1 LL of bilayer graphene, which contains a small component of the N=0 wave function, exhibits an intriguing evolution with increasing magnetic field. Remarkably, the state with the largest energy gap occurs at the crossing of |+1>(|-1>) and |-0> (|+0>) levels, suggesting possible valley orbital coherence. We report on the gap energies of the three FQH states and discuss their possible origins.

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Presenters

  • Ke Huang

    • Pennsylvania State University

Authors

  • Ke Huang

    • Pennsylvania State University

  • Hailong Fu

    • Pennsylvania State 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

  • Chengqi Guo

    • Pennsylvania state University

  • Jun Zhu

    • Pennsylvania State University