Multiple flat bands and topological Hofstadter butterfly in twisted bilayer graphene close to the second magic angle
[1];
[6];
- Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona 08860, Spain,
- Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544,
- Department of Physics, The University of Texas at Austin, Austin, TX 78712,
- Laboratoire National des Champs Magnétiques Intenses, Univ. Grenoble Alpes, UPS-INSA-EMFL-CNRS-LNCMI, 38000 Grenoble, France,
- Department of Physics, University of Basel, Basel 4056, Switzerland,
- National Institute for Materials Science, Tsukuba 305-0044, Japan,
- Department of Physics, Princeton University, Princeton, NJ 08544
Moiré superlattices in two-dimensional van der Waals heterostructures provide an efficient way to engineer electron band properties. The recent discovery of exotic quantum phases and their interplay in twisted bilayer graphene (tBLG) has made this moiré system one of the most renowned condensed matter platforms. So far studies of tBLG have been mostly focused on the lowest two flat moiré bands at the first magic angle θm1~ 1.1°, leaving high-order moiré bands and magic angles largely unexplored. Here we report an observation of multiple well-isolated flat moiré bands in tBLG close to the second magic angle θm2 ~ 0.5°, which cannot be explained without considering electron–election interactions. With high magnetic field magnetotransport measurements we further reveal an energetically unbound Hofstadter butterfly spectrum in which continuously extended quantized Landau level gaps cross all trivial band gaps. The connected Hofstadter butterfly strongly evidences the topologically nontrivial textures of the multiple moiré bands. Overall, our work provides a perspective for understanding the quantum phases in tBLG and the fractal Hofstadter spectra of multiple topological bands.
- Research Organization:
- Univ. of Texas, Austin, TX (United States); Princeton Univ., NJ (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-02ER45958; de-sc0016239; SC0016239
- OSTI ID:
- 1809913
- Alternate ID(s):
- OSTI ID: 1849409
- 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 Vol. 118 Journal Issue: 30; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Correlated Hofstadter spectrum and flavour phase diagram in magic-angle twisted bilayer graphene
All Magic Angles in Twisted Bilayer Graphene are Topological