Robust Interlayer-Coherent Quantum Hall States in Twisted Bilayer Graphene

ORAL

Abstract

We introduce a novel two-dimensional electronic system with ultrastrong interlayer interactions, namely twisted bilayer graphene with a large twist angle, as an ideal ground for realizing interlayer-coherent excitonic condensates. In these systems, subnanometer atomic separation between the layers allows significant interlayer interactions, while interlayer electron tunneling is geometrically suppressed due to the large twist angle. By fully exploiting these two features we demonstrate that a sequence of odd-integer quantum Hall states with interlayer coherence appears at the second Landau level (N = 1). Notably the energy gaps for these states are of order 1 K, which is several orders of magnitude greater than those in GaAs. Furthermore, a variety of quantum Hall phase transitions are observed experimentally. All the experimental observations are largely consistent with our phenomenological model calculations. Hence, we establish that a large twist angle system is an excellent platform for high-temperature excitonic condensation.

* Basic Science Research Program NRF-2020R1C1C1006914 through the National Research Foundation of Korea (NRF)DGIST R&D program (22-CoE-NT-01) of the Korean Ministry of Science and ICTBrainLink program funded by the Ministry of Science and ICT through the National Research Foundation of Korea(2022H1D3A3A01077468)JSPS KAKENHI (Grant Numbers 19H05790, 20H00354 and 21H05233) and A3 Foresight by JSPSNRF of Korea (Grant No. 2020R1C1C1006048) funded by the Korean Government (MSIT)Air Force Office of Scientific Research under Award No. FA2386-20-1-4029 and No. FA2386-22-1-4061acknowledges Samsung Science and Technology Foundation under Project Number SSTF-BA2002-05. B.K.KIAS individual Grant PG069402 at Korea Institute for Advanced Study, and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2020R1F1A1075569).MSIT (Ministry of Science and ICT), Korea, under the ITRC (Information Technology Research Center) support program (IITP-2022-RS-2022-00164799)

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Presenters

  • Dohun Kim

    Daegu Gyeongbuk Institute of Science and Technology

Authors

  • Dohun Kim

    Daegu Gyeongbuk Institute of Science and Technology

  • Byungmin Kang

    Massachusetts Institute of Technology

  • Yong-Bin Choi

    POSTECH

  • Kenji Watanabe

    National Institute for Materials Science, NIMS, Research Center for Electronic and Optical Materials, National Institute for Materials Science, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science

  • Takashi Taniguchi

    Kyoto Univ, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics, Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, National Institute for Materials Sciences, NIMS, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science, International Center for Materials Nanoarchitectonics, NIMS, Japan, International Center for Materials Nanoarchitectonics, Tsukuba, National Institue for Materials Science, Kyoto University, National Institute of Materials Science, International Center for Materials Nanoarchitectonics and National Institute for Materials Science

  • Gil-Ho Lee

    Pohang Univ of Sci & Tech

  • Gil Young Cho

    Pohang Univ of Sci & Tech

  • Youngwook Kim

    DGIST, Daegu Gyeongbuk Institute for Science and Technology