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Electrical switching of magnetic order in an orbital Chern insulator

Author

Listed:
  • H. Polshyn

    (University of California, Santa Barbara)

  • J. Zhu

    (University of Texas)

  • M. A. Kumar

    (University of California, Santa Barbara)

  • Y. Zhang

    (University of California, Santa Barbara)

  • F. Yang

    (University of California, Santa Barbara)

  • C. L. Tschirhart

    (University of California, Santa Barbara)

  • M. Serlin

    (University of California, Santa Barbara)

  • K. Watanabe

    (National Institute for Materials Science)

  • T. Taniguchi

    (National Institute for Materials Science)

  • A. H. MacDonald

    (University of Texas)

  • A. F. Young

    (University of California, Santa Barbara)

Abstract

Magnetism typically arises from the joint effect of Fermi statistics and repulsive Coulomb interactions, which favours ground states with non-zero electron spin. As a result, controlling spin magnetism with electric fields—a longstanding technological goal in spintronics and multiferroics1,2—can be achieved only indirectly. Here we experimentally demonstrate direct electric-field control of magnetic states in an orbital Chern insulator3–6, a magnetic system in which non-trivial band topology favours long-range order of orbital angular momentum but the spins are thought to remain disordered7–14. We use van der Waals heterostructures consisting of a graphene monolayer rotationally faulted with respect to a Bernal-stacked bilayer to realize narrow and topologically non-trivial valley-projected moiré minibands15–17. At fillings of one and three electrons per moiré unit cell within these bands, we observe quantized anomalous Hall effects18 with transverse resistance approximately equal to h/2e2 (where h is Planck’s constant and e is the charge on the electron), which is indicative of spontaneous polarization of the system into a single-valley-projected band with a Chern number equal to two. At a filling of three electrons per moiré unit cell, we find that the sign of the quantum anomalous Hall effect can be reversed via field-effect control of the chemical potential; moreover, this transition is hysteretic, which we use to demonstrate non-volatile electric-field-induced reversal of the magnetic state. A theoretical analysis19 indicates that the effect arises from the topological edge states, which drive a change in sign of the magnetization and thus a reversal in the favoured magnetic state. Voltage control of magnetic states can be used to electrically pattern non-volatile magnetic-domain structures hosting chiral edge states, with applications ranging from reconfigurable microwave circuit elements to ultralow-power magnetic memories.

Suggested Citation

  • H. Polshyn & J. Zhu & M. A. Kumar & Y. Zhang & F. Yang & C. L. Tschirhart & M. Serlin & K. Watanabe & T. Taniguchi & A. H. MacDonald & A. F. Young, 2020. "Electrical switching of magnetic order in an orbital Chern insulator," Nature, Nature, vol. 588(7836), pages 66-70, December.
  • Handle: RePEc:nat:nature:v:588:y:2020:i:7836:d:10.1038_s41586-020-2963-8
    DOI: 10.1038/s41586-020-2963-8
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    Citations

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    Cited by:

    1. Pratap Chandra Adak & Subhajit Sinha & Debasmita Giri & Dibya Kanti Mukherjee & Chandan & L. D. Varma Sangani & Surat Layek & Ayshi Mukherjee & Kenji Watanabe & Takashi Taniguchi & H. A. Fertig & Arij, 2022. "Perpendicular electric field drives Chern transitions and layer polarization changes in Hofstadter bands," Nature Communications, Nature, vol. 13(1), pages 1-8, December.
    2. J. Díez-Mérida & A. Díez-Carlón & S. Y. Yang & Y.-M. Xie & X.-J. Gao & J. Senior & K. Watanabe & T. Taniguchi & X. Lu & A. P. Higginbotham & K. T. Law & Dmitri K. Efetov, 2023. "Symmetry-broken Josephson junctions and superconducting diodes in magic-angle twisted bilayer graphene," Nature Communications, Nature, vol. 14(1), pages 1-7, December.
    3. Le Liu & Shihao Zhang & Yanbang Chu & Cheng Shen & Yuan Huang & Yalong Yuan & Jinpeng Tian & Jian Tang & Yiru Ji & Rong Yang & Kenji Watanabe & Takashi Taniguchi & Dongxia Shi & Jianpeng Liu & Wei Yan, 2022. "Isospin competitions and valley polarized correlated insulators in twisted double bilayer graphene," Nature Communications, Nature, vol. 13(1), pages 1-7, December.
    4. Saisab Bhowmik & Bhaskar Ghawri & Youngju Park & Dongkyu Lee & Suvronil Datta & Radhika Soni & K. Watanabe & T. Taniguchi & Arindam Ghosh & Jeil Jung & U. Chandni, 2023. "Spin-orbit coupling-enhanced valley ordering of malleable bands in twisted bilayer graphene on WSe2," Nature Communications, Nature, vol. 14(1), pages 1-8, December.
    5. Hongyun Zhang & Qian Li & Youngju Park & Yujin Jia & Wanying Chen & Jiaheng Li & Qinxin Liu & Changhua Bao & Nicolas Leconte & Shaohua Zhou & Yuan Wang & Kenji Watanabe & Takashi Taniguchi & Jose Avil, 2024. "Observation of dichotomic field-tunable electronic structure in twisted monolayer-bilayer graphene," Nature Communications, Nature, vol. 15(1), pages 1-7, December.
    6. Hao Chen & Arpit Arora & Justin C. W. Song & Kian Ping Loh, 2023. "Gate-tunable anomalous Hall effect in Bernal tetralayer graphene," Nature Communications, Nature, vol. 14(1), pages 1-6, December.
    7. Yungi Jeong & Hangyeol Park & Taeho Kim & Kenji Watanabe & Takashi Taniguchi & Jeil Jung & Joonho Jang, 2024. "Interplay of valley, layer and band topology towards interacting quantum phases in moiré bilayer graphene," Nature Communications, Nature, vol. 15(1), pages 1-9, December.
    8. Si-yu Li & Zhengwen Wang & Yucheng Xue & Yingbo Wang & Shihao Zhang & Jianpeng Liu & Zheng Zhu & Kenji Watanabe & Takashi Taniguchi & Hong-jun Gao & Yuhang Jiang & Jinhai Mao, 2022. "Imaging topological and correlated insulating states in twisted monolayer-bilayer graphene," Nature Communications, Nature, vol. 13(1), pages 1-7, December.
    9. Canxun Zhang & Tiancong Zhu & Tomohiro Soejima & Salman Kahn & Kenji Watanabe & Takashi Taniguchi & Alex Zettl & Feng Wang & Michael P. Zaletel & Michael F. Crommie, 2023. "Local spectroscopy of a gate-switchable moiré quantum anomalous Hall insulator," Nature Communications, Nature, vol. 14(1), pages 1-7, December.

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