Strong-coupling phases of trions and excitons in electron-hole bilayers at commensurate densities

TL;DR

This paper explores novel strongly-coupled phases in electron-hole bilayers at a 2:1 density ratio, revealing quantum crystals and an excitonic supersolid with potential experimental realizations.

Contribution

It introduces a theoretical framework and numerical analysis of strong-coupling phases, including excitonic supersolids, in electron-hole bilayers at specific density ratios.

Findings

Identification of quantum crystals of electrons, excitons, and trions.

Proposal of an excitonic supersolid phase with simultaneous crystallization and superfluidity.

Discussion of experimental signatures in transition metal dichalcogenide bilayers.

Abstract

We introduce density imbalanced electron-hole bilayers at a commensurate 2 : 1 density ratio as a platform for realizing novel phases involving electrons, excitons and trions. Three length scales are identified which characterize the interplay between kinetic energy, intralayer repulsion, and interlayer attraction. By a combination of theoretical analysis and numerical calculation, we find a variety of strong-coupling phases in different parameter regions, including quantum crystals of electrons, excitons, and trions. We also propose an "excitonic supersolid" phase that features electron crystallization and exciton superfluidity simultaneously. The material realization and experimental signature of these phases are discussed in the context of semiconductor transition metal dichalcogenide bilayers.