Article Hetero-Orbital Two-Component Fractional Quantum Hall States in Bilayer Graphene

Ke Huang ; Ajit C. Balram ; Hailong Fu ; Chengqi Guo ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials Science) ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials Science) ; Jainendra K. Jain ; Jun Zhu

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Ke Huang, Ajit C. Balram, Hailong Fu, Chengqi Guo, Kenji Watanabe, Takashi Taniguchi, Jainendra K. Jain, Jun Zhu. Hetero-Orbital Two-Component Fractional Quantum Hall States in Bilayer Graphene. Physical Review X. 2025, 15 (3), 031023. https://doi.org/10.1103/kfn2-qggs

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(abstract)

The nature of the many-body state in a Landau level (LL) is crucially dependent on its orbital wave function. For example, in GaAs quantum wells, the half-filled n = 0, 1, and 2 LLs exhibit a metallic, a fractional quantum Hall (FQH), and a charge density wave state, respectively. Multi-component FQH states of electrons with the same orbital wave function but with different spin or valley components, where the interaction is SU(2)-isotropic, have also been observed. Here we report on the observation and theoretical understanding of a new type of “hetero-orbital” two-component FQH states, which occur at the isospin transition of the N = 0 and 1 electron LLs in bilayer graphene. Surprisingly, the underlying SU(2)-anisotropic interaction also stabilizes two- component FQH states and isospin transitions, which however are markedly different from those in homo-orbital systems. We observe a strong two-component 2/5 state, the energy gap of which surpasses its single-component FQH siblings over a wide range of magnetic field before abruptly disappearing at a high field. The anisotropy also leads to a strong asymmetry between parallel- vortex and reverse-vortex composite fermion states. Combined with detailed theoretical calculations, our work contributes new insights into the robustness of multi-component FQH effect.

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Keyword: fractional quantum Hall (FQH) states
, bilayer graphene
, hetero-orbital


Date published: 2025-07-22

Publisher: American Physical Society (APS)

Journal:

  • Physical Review X (ISSN: 21603308) vol. 15 issue. 3 031023

Funding:

  • Basic Energy Sciences DE-SC0005042
  • Japan Society for the Promotion of Science 21H05233
  • Japan Society for the Promotion of Science 23H02052
  • Core Research for Evolutional Science and Technology JPMJCR24A5
  • Ministry of Education, Culture, Sports, Science and Technology
  • National High Magnetic Field Laboratory
  • Mathematical Research Impact Centric Support MTR/2023/000002
  • World Premier International Research Center Initiative
  • U.S. Department of Energy DE-SC0022947
  • National Science Foundation NSF-DMR-1904986
  • National Science Foundation NSF-DMR-1644779
  • Science and Engineering Research Board
  • Department of Science and Technology, Ministry of Science and Technology, India
  • Institute of Mathematical Sciences

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1103/kfn2-qggs

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Updated at: 2026-03-03 08:30:13 +0900

Published on MDR: 2026-03-02 17:20:29 +0900

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