Correlated electronic states and Fermi surface topology in flat-band graphene layers

Stacking two-dimensional atomic crystals, or applying a spatially periodic potential can radically change their electronic properties. In particular, it is possible to engineer conditions leading to the creation of extremely narrow energy, flat bands, where the quenched kinetic energy facilitates the emergence of correlated electronic states. This talk will highlight two examples where the electronic ground state and Fermi surface topology depend sensitively on the filling of the flat bands: stacked graphene layers^1,2 with a relative twist angle close to a magic value of ~ 1^o, and buckled graphene layers in which a periodically modulated pseudo-magnetic field creates flat electronic bands.
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