Anomalously Enhanced Diffusivity of Moir\'e Excitons via Manipulating the Interplay with Correlated Electrons

TL;DR

This paper demonstrates that the diffusivity of moiré excitons in TMDC heterobilayers can be actively enhanced by manipulating their interaction with correlated electrons, especially near the Mott insulator state, opening new avenues for excitonic device engineering.

Contribution

It reveals how carrier-exciton interactions in TMDC moiré superlattices can be tuned to control exciton diffusivity, particularly showing enhancement near correlated electron states.

Findings

Exciton diffusivity is suppressed at fractional fillings with Wigner crystal formation.

Carrier interactions can reduce moiré potential confinement, enhancing exciton diffusivity.

Significant diffusivity enhancement observed near the Mott insulator state, especially in 0-degree aligned heterobilayers.

Abstract

Semiconducting transitional metal dichalcogenides (TMDCs) moir\'e superlattice provides an exciting platform for manipulating excitons. The in-situ control of moir\'e potential confined exciton would usher in unprecedented functions of excitonic devices but remains challenging. Meanwhile, as a dipolar composite boson, interlayer exciton in the type-II aligned TMDC moir\'e superlattice strongly interacts with fermionic charge carriers. Here, we demonstrate active manipulation of the exciton diffusivity by tuning their interplay with correlated carriers in moir\'e potentials. At fractional fillings where carriers are known to form generalized Wigner crystals, we observed suppressed diffusivity of exciton. In contrast, in Fermi liquid states where carriers dynamically populate all moir\'e traps, the repulsive carrier-exciton interaction can effectively reduce the moir\'e potential confinement seen by the exciton, leading to enhanced diffusivity with the increase of the carrier density. Notably, the exciton diffusivity is enhanced by orders of magnitude near the Mott insulator state, and the enhancement is much more pronounced for the 0-degree than the 60-degree aligned WS2/WSe2 heterobilayer due to the more localized nature of interlayer excitons. Our study inspires further engineering and controlling exotic excitonic states in TMDC moir\'e superlattices for fascinating quantum phenomena and novel excitonic devices.