Moir\'{e} flat Chern bands and correlated quantum anomalous Hall states generated by spin-orbit couplings in twisted homobilayer MoS$_2$

TL;DR

This paper predicts that twisted MoS2 bilayers can host moiré flat bands with nonzero Chern numbers due to spin-orbit coupling and twist-induced symmetry breaking, leading to correlated quantum anomalous Hall states.

Contribution

It introduces a novel mechanism for topological flat bands in twisted MoS2 driven by spin-orbit coupling and twist, and predicts correlated quantum anomalous Hall states at half-filling.

Findings

Moiré flat bands with Chern numbers arise from spin-orbit coupling and twist.

Density interactions induce valley-polarized quantum anomalous Hall states.

Displacement fields influence the topological properties and phase transitions.

Abstract

We predict that in a twisted homobilayer of transition-metal dichalcogenide MoS$_2$, spin-orbit coupling in the conduction band states from $\pm K$ valleys can give rise to moir\'{e} flat bands with nonzero Chern numbers in each valley. The nontrivial band topology originates from a unique combination of angular twist and local mirror symmetry breaking in each individual layer, which results in unusual skyrmionic spin textures in momentum space with skyrmion number $\mathcal{S} = \pm 2$. Our Hartree-Fock analysis further suggests that density-density interactions generically drive the system at $1/2$-filling into a valley-polarized state, which realizes a correlated quantum anomalous Hall state with Chern number $\mathcal{C} = \pm 2$. Effects of displacement fields are discussed with comparison to nontrivial topology from layer-pseudospin magnetic fields.