A moire superlattice on the surface of a topological insulator

Twisting two materials produces moiré patterns and can induce correlated many-body states, as seen in twisted bilayer graphene, for example. We investigate the surface state of a topological insulator subject to a moiré superlattice potential. With diagrammatic perturbation theory, lattice model simulations, and ab initio calculations, we uncover the unique aspects of twisting a single Dirac cone with an induced moiré superlattice and the role of bulk topology on the reconstructed bands. The Dirac cone velocity renormalizes, but no gap opens up; instead, a whole ladder of satellite Dirac cones appears, some of which can be made relatively flat with a large nearby density of states. We discuss the implications of our findings to correlated physics and future experiments.