Nearly flat Chern bands in moiré superlattices

Abstract

The competition between the kinetic energy of electrons in a crystal and the inter-electron Coulomb repulsion underlies many fascinating phenomena in quantum materials. Superlattices formed from moir\'e patterns in graphene structures have emerged as tunable platforms for such physics. This paper shows that in many graphene moir\'e structures not only are the electronic bands narrow enough for Coulomb interaction to be important, but they are also topologically nontrivial. This setting of a strong correlated partially filled topological band promises to lead to many novel phenomena.