Hyperspectral Imaging of Dipole-Ladder-Mediated Exciton Drift in Moiré Superlattices.

Abstract

Moiré superlattices have emerged as a highly tunable platform for exploring correlated bosonic states, such as the recently discovered dipole ladder arising from strong on-site exciton-exciton interactions. Although spectroscopic signatures of these dipole ladders are established, their influence on exciton transport has remained unknown. Here, we employ hyperspectral transient photoluminescence microscopy to directly visualize exciton dynamics in a WS₂/WSe₂ moiré superlattice and demonstrate that dipole ladder mediates highly efficient exciton drift. At high excitation densities, the formation of a transient dipolar ladder generates a steep internal potential gradient. This gradient triggers a transition from localized, diffusion-limited transport (with a diffusion coefficient of <i>D</i> ≈ 0.01 cm² s^-1) to rapid, drift-dominated flow, yielding an equivalent diffusion coefficient of 0.75 cm² s^-1. These results establish dipole ladders as an interaction-driven mechanism for controlling exciton flow in moiré superlattices.