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Valley-controlled even-denominator fractional quantum Hall effect in bilayer graphene

ORAL

Abstract

In a magnetic field, strong electron-electron interaction leads to the celebrated fractional quantum Hall(FQH) effect. FQH states with even-denominators are particularly interesting as they are predicted to host non-Abelian excitations that are foundations of topological quantum computing. Bernal-stacked bilayer graphene has been shown to support even-denominator FQH states at large perpendicular displacement field D at filling factors ν = -5/2, -1/2, 3/2, and 7/2. Here we report the observation of a new even-denominator state at filling factor ν = 5/2 in bilayer graphene. Thanks to higher device quality, we are able to access the regime of very small D-field and probe the gap of the 5/2 state Δ5/2 in the limit of vanishing valley splitting EV. We find that Δ5/2 increases with increasing D and extrapolates to a finite value in the limit of EV = 0. This result indicates the spontaneous valley polarization of the 5/2 state and provides support for the Moore-Read Pfaffian/anti-Pfaffian wave functions. The exquisite control we have in manipulating the valley pseudospin opens the door to exciting valley-coherent many-body phenomena.

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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, 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

  • Xi Lin

    International Center for Quantum Materials, Peking University, Peking Univ, International Center for Quantum Materials, School of Physics, Peking University, Peking University

  • Jun Zhu

    Pennsylvania State University, Physics, The Pennsylvania State University