Twisted bilayer graphene with a twist angle of around 1.1{\deg} features a pair of isolated flat electronic bands and forms a strongly correlated electronic platform. Here, we use scanning tunneling microscopy to probe local properties of highly tunable twisted bilayer graphene devices and show that the flat bands strongly deform when aligned with the Fermi level. At half filling of the bands, we observe the development of gaps originating from correlated insulating states. Near charge neutrality, we find a previously unidentified correlated regime featuring a substantially enhanced flat band splitting that we describe within a microscopic model predicting a strong tendency towards nematic ordering. Our results provide insights into symmetry breaking correlation effects and highlight the importance of electronic interactions for all filling factors in twisted bilayer graphene.
@article{arxiv.1901.02997,
title = {Imaging Electronic Correlations in Twisted Bilayer Graphene near the Magic Angle},
author = {Youngjoon Choi and Jeannette Kemmer and Yang Peng and Alex Thomson and Harpreet Arora and Robert Polski and Yiran Zhang and Hechen Ren and Jason Alicea and Gil Refael and Felix von Oppen and Kenji Watanabe and Takashi Taniguchi and Stevan Nadj-Perge},
journal= {arXiv preprint arXiv:1901.02997},
year = {2019}
}
Comments
Main text 9 pages, 4 figures; Supplementary Information 25 pages