Polarization-driven band topology evolution in twisted MoTe_2 and WSe_2

Motivated by recent experimental observations of opposite Chern numbers in R-type twisted MoTe_2 and WSe_2 homobilayers, we perform large-scale density-functional-theory (DFT) calculations with machine learning force fields to investigate moiré band topology from large to small twist angels in both materials. We find that the Chern numbers of the moiré frontier bands change sign as a function of twist angle, and this change is driven by the competition between the in-plane piezoelectricity and the out-of-plane ferroelectricity. Our large-scale calculations, enabled by machine learning methods, reveal crucial insights into interactions across different scales in twisted bilayer systems. The interplay between atomic-level relaxation effects and moiré-scale electrostatic potential variation opens new avenues for the design of intertwined topological and correlated states.