Observation of flat bands in twisted bilayer graphene

Simone Lisi, Xiaobo Lu, Tjerk Benschop, Tobias A. de Jong, Petr Stepanov, Jose R. Duran, Florian Margot, Irène Cucchi, Maarten Leeuwenhoek, More Authors

Research output: Contribution to journalLetterScientificpeer-review

Abstract

Transport experiments in twisted bilayer graphene have revealed multiple superconducting domes separated by correlated insulating states1–5. These properties are generally associated with strongly correlated states in a flat mini-band of the hexagonal moiré superlattice as was predicted by band structure calculations6–8. Evidence for the existence of a flat band comes from local tunnelling spectroscopy9–13 and electronic compressibility measurements14, which report two or more sharp peaks in the density of states that may be associated with closely spaced Van Hove singularities. However, direct momentum-resolved measurements have proved to be challenging15. Here, we combine different imaging techniques and angle-resolved photoemission with simultaneous real- and momentum-space resolution (nano-ARPES) to directly map the band dispersion in twisted bilayer graphene devices near charge neutrality. Our experiments reveal large areas with a homogeneous twist angle that support a flat band with a spectral weight that is highly localized in momentum space. The flat band is separated from the dispersive Dirac bands, which show multiple moiré hybridization gaps. These data establish the salient features of the twisted bilayer graphene band structure.

Original languageEnglish
Number of pages6
JournalNature Physics
DOIs
Publication statusPublished - 2020

Fingerprint Dive into the research topics of 'Observation of flat bands in twisted bilayer graphene'. Together they form a unique fingerprint.

Cite this