Observation of Reentrant Correlated Insulators and Interaction-Driven Fermi-Surface Reconstructions at One Magnetic Flux Quantum per Moiré Unit Cell in Magic-Angle Twisted Bilayer Graphene

Ipsita Das, Cheng Shen, Alexandre Jaoui, Jonah Herzog-Arbeitman, Aaron Chew, Chang Woo Cho, Kenji Watanabe, Takashi Taniguchi, Benjamin A. Piot, B. Andrei Bernevig, Dmitri K. Efetov

Research output: Contribution to journalArticlepeer-review

Abstract

The discovery of flat bands with nontrivial band topology in magic-angle twisted bilayer graphene (MATBG) has provided a unique platform to study strongly correlated phenomena including superconductivity, correlated insulators, Chern insulators, and magnetism. A fundamental feature of the MATBG, so far unexplored, is its high magnetic field Hofstadter spectrum. Here, we report on a detailed magnetotransport study of a MATBG device in external magnetic fields of up to B=31 T, corresponding to one magnetic flux quantum per moiré unit cell φ0. At φ0, we observe reentrant correlated insulators at a flat band filling factors of ν=+2 and of ν=+3, and interaction-driven Fermi-surface reconstructions at other fillings, which are identified by new sets of Landau levels originating from these. These experimental observations are supplemented by theoretical work that predicts a new set of eight well-isolated flat bands at φ0, of comparable band width, but with different topology than in zero field. Overall, our magnetotransport data reveal a qualitatively new Hofstadter spectrum in MATBG, which arises due to the strong electronic correlations in the reentrant flat bands.

Original languageEnglish (US)
Article number217701
JournalPhysical review letters
Volume128
Issue number21
DOIs
StatePublished - May 27 2022

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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