Twelve-fold degenerate quantum Hall state in near 30°-twisted bilayer graphene

ORAL

Abstract

Twisted bilayer graphene (tBLG) has attracted tremendous interest but so far has mostly focused on the use of small twist angles. One of the major reasons is that the interlayer coupling between the incommensurate layers, which is normally the case of a large-angle-tBLG, was generally negligible and hence exotic quantum phases of matter are rarely expected. However, when the twist angle is rotated to near 30°, it becomes a very different story. The tBLG forms into dodecagonal quasicrystal with electronic properties distinct from the conventional periodic tBLG [1, 2]. It remains a challenge to explore these quasicrystalline tBLG states through the electrical transport measurements. Here, we use dry transfer methods to fabricate near 30°-tBLG devices and observe an anomalous anti-symmetry of quantum Hall plateaus. Moreover, a robust 12-fold degeneracy is observed in the quantum Hall regime up to ~60 K in both electron and hole transport.

[1] Ahn, S. J. et al. Dirac electrons in a dodecagonal graphene quasicrystal. Science 361, 782–786 (2018).

[2] Yao, W. et al. Quasicrystalline 30° twisted bilayer graphene as an incommensurate superlattice with strong interlayer coupling. Proc. Natl. Acad. Sci. USA 115, 6928–6933 (2018).

*Supported by the National Science and Technology Council (Taiwan).

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Presenters

  • Kuo-En Chang

    • National Cheng Kung University, Taiwan

Authors

  • Kuo-En Chang

    • National Cheng Kung University, Taiwan

  • Sheng-Chin Ho

    • National Cheng Kung University, Taiwan

  • Yu-Chiang Hsieh

    • National Cheng Kung University, Taiwan

  • Chiu-Hua Huang

    • National Cheng Kung University, Taiwan

  • Ching-Hua Kao

    • National Cheng Kung University, Taiwan

  • Li-An Wen

    • National Cheng Kung University, Taiwan

  • 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

  • Tse-Ming Chen

    • National Cheng Kung University, Taiwan