Band mixing in the quantum anomalous Hall regime of twisted semiconductor bilayers

TL;DR

This paper investigates how band mixing influences the energetics and phase diagram of twisted semiconductor bilayers exhibiting fractional quantum anomalous Hall effects, providing insights into their complex correlated states.

Contribution

It offers a comprehensive numerical analysis of band mixing effects across twist angles, advancing understanding of the phase diagram in twisted semiconductor bilayers.

Findings

Band mixing significantly affects energy gaps and state energetics.

Qualitative and quantitative impacts on competing states.

Establishes groundwork for realistic studies of correlated twisted multilayers.

Abstract

Remarkable recent experiments have observed fractional quantum anomalous Hall (FQAH) effects at zero field and unusually high temperatures in twisted semiconductor bilayer $t$MoTe$_2$. Intriguing observations in these experiments such as the absence of integer Hall effects at twist angles where a fractional Hall effect is observed, do however remain unexplained. The experimental phase diagram as a function of twist angle remains to be established. By comprehensive numerical study, we show that band mixing has large qualitative and quantitative effects on the energetics of competing states and their energy gaps throughout the twist angle range $\theta\leq 4^\circ$. This lays the ground for the detailed realistic study of a rich variety of strongly correlated twisted semiconductor multilayers and an understanding of the phase diagram of these fascinating systems.