Physics Colloquium - "Exotic Phases in Moire Systems" Presented by Professor Bogdan Andrei Bernevig, Princeton University

I will review the experimental discoveries and amazing puzzles in Twisted Bilayer Graphene and in twisted MoTe2 which culminated with the discovery of long-thought phases of matter such as the Fractional Chern Insulator. We will then show that, theoretically, most of the puzzling properties of TBG can be explained by an exact analytic mapping of the problem to a topological heavy fermion system. This mapping links two seemingly completely different fields but, in retrospect represents a natural way of explaining all the experimental puzzles. In The MoTe2, we will show how the FCI states discovered are more complicated than initially thought, and how a correct description of the intricate nature of the system necessarily involves band mixing, which exponentially increases the difficulty of the problem.