Electrically tuned topology and magnetism in twisted bilayer MoTe$_2$ at $\nu_h=1$

TL;DR

This paper theoretically explores how electric fields and twist angles influence the magnetic and topological phases in twisted bilayer MoTe$_2$, revealing electrically switchable magnetic states and phase transitions.

Contribution

It provides a detailed phase diagram of twisted bilayer MoTe$_2$ at $ u_h=1$, highlighting electric field control of magnetic and topological phases, including switching of spin chirality.

Findings

Quantum anomalous Hall insulators appear at intermediate twist angles.

Electric fields can switch spin vector chirality in antiferromagnetic states.

Multiple phase transitions occur with increasing out-of-plane electric potential.

Abstract

We present a theoretical study of an interaction-driven quantum phase diagram of twisted bilayer MoTe$_2$ at hole filling factor $\nu_h=1$ as a function of twist angle $\theta$ and layer potential difference $V_z$, where $V_z$ is generated by an applied out-of-plane electric field. At $V_z=0$, the phase diagram includes quantum anomalous Hall insulators in the intermediate $\theta$ regime and topologically trivial multiferroic states with coexisting ferroelectricity and magnetism in both small and large $\theta$ regimes. There can be two transitions from the quantum anomalous Hall insulator phase to topologically trivial out-of-plane ferromagnetic phase, and finally to in-plane 120$^\circ$ antiferromagnetic phase as $|V_z|$ increases, or a single transition without the intervening ferromagnetic phase. We show explicitly that the spin vector chirality of various 120$^\circ$ antiferromagnetic states can be electrically switched. We discuss the connection between the experimentally measured Curie-Weiss temperature and the low-temperature magnetic order based on an effective Heisenberg model with magnetic anisotropy.