Massive Dirac fermions in moir\'e superlattices: a route towards topological flat minibands

TL;DR

This paper presents a general method to create topological flat minibands in moiré superlattices by confining massive Dirac fermions, enabling the realization of topological phases and correlated insulators in transition metal dichalcogenide heterobilayers.

Contribution

It introduces a universal mechanism for topological miniband formation in moiré systems and demonstrates its application in MoTe2/WSe2 heterobilayers, revealing new topological states.

Findings

Topological flat minibands can be realized in moiré superlattices.

A topological phase is protected by moiré potential symmetry.

Correlated Chern insulator and quantum valley-spin Hall insulator observed.

Abstract

We demonstrate a generic mechanism to realize topological flat minibands by confining massive Dirac fermions in a periodic moir\'e 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 moir\'e potential and survive to arbitrarily large Dirac band gap. We take the MoTe$_2$/WSe$_2$ 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 MoTe$_2$/WSe$_2$ in experiment. Our work clarifies the importance of Dirac structure for the topological minibands and unveils a general strategy to design topological moir\'e materials.