Excitonic Tonks-Girardeau and charge-density wave phases in monolayer semiconductors

TL;DR

This paper predicts and analyzes the transition of excitonic systems in monolayer semiconductors from a Tonks-Girardeau to a charge-density-wave phase, highlighting experimental signatures in photoluminescence spectra.

Contribution

It introduces a realistic model for exciton interactions in 2D semiconductors and identifies observable signatures of many-body phase crossover.

Findings

Identification of a crossover from Tonks-Girardeau to charge-density-wave regimes

Prediction of key features in pair correlation functions

Photoluminescence spectra as experimental fingerprints

Abstract

Excitons in two-dimensional semiconductors provide a novel platform for fundamental studies of many-body interactions. In particular, dipolar interactions between spatially indirect excitons may give rise to strongly correlated phases of matter that so far have been out of reach of experiments. Here, we show that excitonic few-body systems in atomically thin transition-metal dichalcogenides undergo a crossover from a Tonks-Girardeau to a charge-density-wave regime. To this end, we take into account realistic system parameters and predict the effective exciton-exciton interaction potential. We find that the pair correlation function contains key signatures of the many-body crossover already at small exciton numbers and show that photoluminescence spectra provide readily accessible experimental fingerprints of these strongly correlated quantum many-body states.