Supermoiré-Trapped Quadrupolar Exciton

Abstract

Moiré-trapped dipolar interlayer excitons in heterobilayers offer a rich platform to explore interaction-driven phenomena. Extending to three layers and beyond leads to highly intriguing multipolar excitons─a superposition state of vertically aligned phase-coherent excitons. However, in experiments, unintentional twist-angle mismatches among layers may degrade the strength and homogeneity of the vertical Coulomb coupling. Here we propose that the supermoiré effect in a hetero-trilayer comes to the rescue by creating periodic pockets of vertically aligned atomic registries that facilitate the formation of quadrupolar excitons trapped in such pockets. Using a WS2/WSe2/WS2 stack, we show interactions between multiple confined levels of the top and bottom moiré interfaces, creating electric field tunable multilevel hybridized bright (symmetric) and dark (antisymmetric) quadrupolar states. Our work underscores the critical role of the supermoiré effect in quadrupolar excitons. The discovery of reduced sensitivity on precise angle alignment will ignite exploration of complex excitonic states in multilayered heterostructures.