2026/07/24 by Anish Kumar, Suman Chatterjee, Kenji Watanabe +2
#cond-mat.mes-hall #cond-mat.mtrl-sci #physics.optics
Moiré-trapped dipolar interlayer exciton in heterobilayers offers a rich platform to explore interaction-driven phenomena. Extending the number of layers to three and beyond leads to highly intriguing multipolar exciton - a superposition state of vertically aligned phase-coherent excitons. However, in experiments, unintentional twist-angle mismatch among layers may degrade the strength and homogeneity of the vertical Coulomb coupling. Here we propose that the supermoiré effect in a heterotrilayer 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 WS2/WSe2/WS2 stack, we show interaction between multiple confined levels of the top and bottom moiré interfaces, creating electric field tunable multi-level hybridized bright (symmetric) and dark (anti-symmetric) quadrupolar states. Our work underscores the critical role of supermoiré effect in quadrupolar excitons. The discovery of reduced sensitivity on precise angle-alignment will ignite exploration of complex excitonic states in multi-layered heterostructures.