Stabilizing fractional Chern insulators via exchange interaction in moir\'e systems

TL;DR

This paper shows how exchange interactions in moiré systems can tune band topology and stabilize fractional Chern insulators, revealing phase transitions and broadening conditions for their realization.

Contribution

Demonstrates that exchange interactions induced by proximity effect can tune topology and bandwidth in moiré minibands, enabling stable fractional Chern insulators over a wide range of twist angles.

Findings

Fractional Chern insulators appear at -2/3 filling with enhanced gaps.

Topological phase transition between fractional Chern insulator, quantum anomalous Hall, and charge density wave.

Enlarged twist angles support fractional Chern insulators with increased stability.

Abstract

Recent experimental discovery of fractional Chern insulator in moir\'e Chern band in twisted transition metal dichalocogenide homobilayers has sparked intensive interest in exploring the ways of engineering band topology and correlated states in moir\'e systems. In this letter, we demonstrate that, with an additional exchange interaction induced by proximity effect, the topology and bandwidth of the moir\'e minibands of twisted $\mathrm{MoTe_2}$ homobilayers can be easily tuned. Fractional Chern insulators at -2/3 filling are found to appear at enlarged twist angles over a large range of twist angles with enhanced many-body gaps. We further discover a topological phase transition between the fractional Chern insulator, quantum anomalous Hall crystal, and charge density wave. Our results shed light on the interplay between topology and correlation physics.