Massive Dirac fermions in moiré superlattices: A route towards topological flat minibands and correlated topological insulators

We demonstrate a generic mechanism to realize topological flat minibands by confining massive Dirac fermions in a periodic moiré potential, which can be achieved in a heterobilayer of transition metal dichalcogenides. We show that the topological phase can be protected by the symmetry of moiré potential and survive to arbitrarily large Dirac band gap. We take the MoTe2/WSe2 heterobilayer as an example and find that the topological phase can be driven by a vertical electric field. By projecting the Coulomb interaction onto the topological fat minibands, we identify a correlated Chern insulator at half filling and a quantum valley-spin Hall insulator at full filling which explains the topological states observed in the MoTe2/WSe2 in the experiment. Our work clarifies the importance of Dirac structure for the topological minibands and unveils a general strategy to design topological moiré materials.