Seminar By Louk Rademaker, Université de Genève, Switzerland
Title: Symmetry breaking and Chern insulators in twisted graphene structures
Host: Oskar Vafek
Abstract: Twisted bilayer graphene (tBG) and variants like twisted monolayer-bilayer graphene (tMBG) were proposed to be a platform for strongly correlated physics akin to the cuprate family. However, I will show that many of the observed interacting phenomena can be explained in terms of breaking of spin/valley symmetry.
To do so, I will first describe how flat bands in tBG can be directly observed using ARPES . An effective description of the flat bands is hampered by band renormalization due to charge transfer  and band topology.
The combination of interactions and topology naturally leads to spin/valley symmetry breaking with a quantum anomalous Hall effect in tMBG . In tBG in large magnetic fields, similar spin/valley symmetry breaking creates a series of Chern insulator states . I will conclude with a brief discussion of the possibility of genuine strong correlations in Moiré structures.
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