Gate-tunable antiferromagnetic Chern insulator in twisted bilayer transition metal dichalcogenides

TL;DR

This paper predicts a gate-tunable antiferromagnetic Chern insulator in twisted bilayer MoTe2, revealing new topological phases driven by electron correlations and external electric fields at specific twist angles.

Contribution

It introduces the concept of an antiferromagnetic Chern insulator in twisted bilayer MoTe2, expanding the understanding of topological phases beyond previously observed states.

Findings

Antiferromagnetic Chern insulator stabilized by electric field.

Phase diagram similar to Kane-Mele-Hubbard model.

Most evident at a twist angle of approximately 4 degrees.

Abstract

A series of recent experimental works on twisted MoTe$_2$ homobilayers have unveiled an abundance of exotic states in this system. Valley-polarized quantum anomalous Hall states have been identified at hole doping of $\nu = -1$, and the fractional quantum anomalous Hall effect is observed at $\nu = -2/3$ and $\nu = -3/5$. In this work, we investigate the electronic properties of AA-stacked twisted bilayer MoTe$_2$ at $\nu=-2$ by $k$-space Hartree-Fock calculations. We find that the phase diagram is qualitatively similar to the phase diagram of a Kane-Mele-Hubbard with staggered onsite potential. A noteworthy phase within the diagram is the antiferromagnetic Chern insulator, stabilized by the external electric field. We attribute the existence of this Chern insulator to an antiferromagnetic instability at a topological phase transition between the quantum spin hall phase and a band insulator phase. We highlight that the antiferromagnetic Chern insulator phase is most evident at a twist angle of approximately $4^\circ$. Our research proposes the potential of realizing a Chern insulator beyond $\nu=-1$, and contributes fresh perspectives on the interplay between band topology and electron-electron correlations in moir\'e superlattices.