Multiple flat bands and topological Hofstadter butterfly in twisted bilayer graphene close to the second magic angle

Journal Article · 22 July 2021 · Proceedings of the National Academy of Sciences of the United States of America

DOI: https://doi.org/10.1073/pnas.2100006118 · OSTI ID:1809913

Lu, Xiaobo  ^[1]; Lian, Biao ^[2]; Chaudhary, Gaurav ^[3]; Piot, Benjamin A. ^[4]; Romagnoli, Giulio ^[5]; Watanabe, Kenji  ^[6]; Taniguchi, Takashi ^[6]; Poggio, Martino ^[5]; MacDonald, Allan H. ^[3]; Bernevig, B. Andrei ^[7]; Efetov, Dmitri K. ^[1]

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1. Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona 08860, Spain,
2. Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544,
3. Department of Physics, The University of Texas at Austin, Austin, TX 78712,
4. Laboratoire National des Champs Magnétiques Intenses, Univ. Grenoble Alpes, UPS-INSA-EMFL-CNRS-LNCMI, 38000 Grenoble, France,
5. Department of Physics, University of Basel, Basel 4056, Switzerland,
6. National Institute for Materials Science, Tsukuba 305-0044, Japan,
7. Department of Physics, Princeton University, Princeton, NJ 08544

Significance Multiple flat bands in high-quality twisted bilayer graphene close to the theoretically predicted second magic angle are observed. These well-isolated flat moiré bands host a nontrivial topology which is evidenced by a connecting multiband Hofstadter butterfly spectrum. This work provides a perspective for understanding the emergent quantum phases (i.e., strong correlation and band topology) in twisted bilayer graphene and the fractal Hofstadter spectra of multiple topological bands.

• Research Organization: Princeton Univ., NJ (United States); Univ. of Texas, Austin, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FG02-02ER45958; SC0016239
• OSTI ID: 1809913
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 30 Vol. 118; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of SciencesCopyright Statement
• Country of Publication: United States
• Language: English