Correlated insulator of excitons in WSe2/WS2 moir\'e superlattices

TL;DR

This paper reports the discovery of a bosonic correlated insulator of excitons in WSe2/WS2 moiré superlattices, revealing a new platform for engineering exotic bosonic quantum phases.

Contribution

The study introduces a pump probe spectroscopy method to observe exciton incompressible states and demonstrates the transition between excitonic and electronic correlated insulators in moiré superlattices.

Findings

Observation of an exciton incompressible state at ν_ex=1

Transition from exciton to electron correlated insulator with charge density

Establishment of semiconducting moiré superlattices as a platform for bosonic phases

Abstract

A panoply of unconventional electronic states has been observed in moir\'e superlattices. Engineering similar bosonic phases remains, however, largely unexplored. We report the observation of a bosonic correlated insulator in WSe2/WS2 moir\'e superlattices composed of excitons, i.e., tightly bound electron-hole pairs. We develop a pump probe spectroscopy method that we use to observe an exciton incompressible state at exciton filling {\nu}_ex = 1 and charge neutrality, indicating a correlated insulator of excitons. With varying charge density, the bosonic correlated insulator continuously transitions into an electron correlated insulator at charge filling {\nu}_e = 1, suggesting a mixed correlated insulating state between the two limits. Our studies establish semiconducting moir\'e superlattices as an intriguing platform for engineering bosonic phases.