Exciton-based sensing of remote electron correlations in 2D heterostructures

TL;DR

This paper develops a theoretical framework to interpret how excitonic resonance frequencies in 2D heterostructures are affected by remote electron correlations, aiding in the detection of correlated electron states.

Contribution

It provides a quantitative theory for excitonic frequency shifts caused by long-range Coulomb interactions in 2D heterostructures, enhancing understanding of excitonic sensing.

Findings

The theory accurately predicts frequency shifts in WSe₂ near graphene layers.

Excitonic sensing can detect transitions in remote electron fluids.

Application to WSe₂ demonstrates practical utility.

Abstract

Many monolayer transition metal dichalcogenides, including MoS$_2$, MoSe$_2$, WS$_2$, and WSe$_2$, are direct bandgap two-dimensional (2D) semiconductors with sharp optical resonances at excitonic bound state frequencies. Recent experiments have demonstrated that excitonic resonance frequencies in multilayer van der Waals stacks are altered by long-range Coulomb interactions with electrons in nearby but electrically isolated 2D materials. These modulations have been successfully used to detect transitions between distinct states of remote strongly correlated 2D electron fluids. In this Letter we provide a theory of these frequency shifts, enabling a more quantitative interpretation of excitonic-sensing experiments, and apply it as an example to WSe$_2$ that is proximate to graphene bilayers and multilayers.