Article Interplay of valley, layer and band topology towards interacting quantum phases in moiré bilayer graphene

Yungi Jeong ORCID ; Hangyeol Park ; Taeho Kim ORCID ; Kenji Watanabe SAMURAI ORCID ; Takashi Taniguchi SAMURAI ORCID ; Jeil Jung ORCID ; Joonho Jang ORCID

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Yungi Jeong, Hangyeol Park, Taeho Kim, Kenji Watanabe, Takashi Taniguchi, Jeil Jung, Joonho Jang. Interplay of valley, layer and band topology towards interacting quantum phases in moiré bilayer graphene. Nature Communications. 2024, 15 (1), 6351. https://doi.org/10.1038/s41467-024-50475-x

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(abstract)

In Bernal-stacked bilayer graphene (BBG), the Landau levels give rise to an intimate connection between valley and layer degrees of freedom. Adding a
moiré superlattice potential enriches the BBG physics with the formation of topological minibands — potentially leading to tunable exotic quantum transport. Here, we present magnetotransport measurements of a high-quality bilayer graphene–hexagonal boron nitride (hBN) heterostructure. The zero- degree alignment generates a strong moiré superlattice potential for the electrons in BBG and the resulting Landau fan diagram of longitudinal and Hall resistance displays a Hofstadter butterfly pattern with a high level of detail. We demonstrate that the intricate relationship between valley and layer degrees of freedom controls the topology of moiré-induced bands, significantly influen- cing the energetics of interacting quantum phases in the BBG superlattice. We further observe signatures of field-induced correlated insulators, helical edge states and clear quantizations of interaction-driven topological quantum phases, such as symmetry broken Chern insulators.

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Keyword: Bilayer graphene, Landau levels, topological minibands

Date published: 2024-07-28

Publisher: Springer Science and Business Media LLC

Journal:

  • Nature Communications (ISSN: 20411723) vol. 15 issue. 1 6351

Funding:

  • National Research Foundation of Korea 2019R1C1C1006520
  • National Research Foundation of Korea 2020R1A5A1016518
  • National Research Foundation of Korea RS-2023-00258359
  • MEXT | Japan Society for the Promotion of Science 21H05233
  • MEXT | Japan Society for the Promotion of Science 23H02052
  • MEXT | Japan Society for the Promotion of Science 21H05233
  • MEXT | Japan Society for the Promotion of Science 23H02052

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

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First published URL: https://doi.org/10.1038/s41467-024-50475-x

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Updated at: 2025-02-05 16:30:30 +0900

Published on MDR: 2025-02-05 16:30:30 +0900

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