Exciton condensate in bilayer transition metal dichalcogenides: strong coupling regime

TL;DR

This paper investigates exciton condensation in bilayer transition metal dichalcogenides, revealing that strong coupling effects significantly influence the condensate's properties and can predict room temperature condensation.

Contribution

It provides a multi-level theoretical analysis including GW approximation to account for screening and quasiparticle renormalization in strong coupling regimes.

Findings

Room temperature exciton condensate predicted by mean field theory

Quasiparticle renormalization reverses mean field predictions

Intralayer interactions strongly affect the order parameter

Abstract

Exciton condensation in an electron-hole bilayer system of monolayer transition metal dichalcogenides is analyzed at three different levels of theory to account for screening and quasiparticle renormalization. The large effective masses of the transition metal dichalcogenides place them in a strong coupling regime. In this regime, mean field (MF) theory with either an unscreened or screened interlayer interaction predicts a room temperature condensate. Interlayer and intralayer interactions renormalize the quasiparticle dispersion, and this effect is included in a GW approximation. The renormalization reverses the trends predicted from the unscreened or screened MF theories. In the strong coupling regime, intralayer interactions have a large impact on the magnitude of the order parameter and its functional dependencies on effective mass and carrier density.