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Rhombohedral stacked multilayer graphene hosts a pair of flat bands touching at zero energy, which should give rise to correlated electron phenomena that can be further tuned by an electric field. Furthermore, when electron correlation breaks the isospin symmetry, the valley-dependent Berry phase at zero energy may give rise to topologically non-trivial states. Here, we measure electron transport through hBN-encapsulated pentalayer graphene down to 100 mK. We observed a correlated insulating state with resistance R>MΩ at charge density n=0 and displacement field D=0. Tight-binding calculations predict a metallic ground state under these conditions. By increasing D, we observed a Chern insulator state with C = -5 and two other states with C = -3 at magnetic field around 1 T. At high D and n, we observed isospin-polarized quarter- and half-metals. Hence, rhombohedral pentalayer graphene exhibits two different types of Fermi-surface instabilities, one driven by a pair of flat bands touching at zero energy, and one induced by the Stoner mechanism in a single flat band. Our results establish rhombohedral multilayer graphene as suitable system to explore intertwined electron correlation and topology phenomena in natural graphitic materials without the need for moiré superlattice engineering.

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• In Copyright
  

  This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1038/s41565-023-01520-1

Keyword: Rhombohedral multilayer graphene, Flat bands, Chern insulator

Date published: 2023-10-05

Publisher: Springer Science and Business Media LLC

Journal:

• Nature Nanotechnology (ISSN: 17483395) vol. 19 issue. 2 p. 181-187

Funding:

• MEXT | Japan Society for the Promotion of Science 20H00354
• 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 20H00354
• MEXT | Japan Society for the Promotion of Science 21H05233
• National Science Foundation DMR-2225925
• National Science Foundation DMR-1231319
• National Science Foundation DMR-2128556*
• National Science Foundation 2225925
• National Science Foundation 2225925
• National Science Foundation PHY-1506284
• National Science Foundation PHY-1506284
• National Science Foundation PHY-1506284
• National Science Foundation 2225925
• National Science Foundation PHY-1506284
• United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research FA9550-21-1-0216
• United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research FA9550-21-1-0216
• United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research FA9550-21-1-0216
• United States Department of Defense | United States Air Force | AFMC | Air Force Office of Scientific Research FA9550-21-1-0216
• MEXT | Japan Society for the Promotion of Science 23H02052

Manuscript type: Author's version (Accepted manuscript)

MDR DOI:

First published URL: https://doi.org/10.1038/s41565-023-01520-1

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Updated at: 2025-09-02 08:30:26 +0900

Published on MDR: 2025-09-02 08:17:16 +0900