Striped excitonic (super)solid in anisotropic semiconductors with screened exciton interactions

TL;DR

This paper predicts a novel striped excitonic supersolid phase in anisotropic semiconductors, caused by screened exciton interactions, using a Gross-Pitaevskii model, with potential realization in materials like black phosphorus.

Contribution

It introduces the concept of a striped excitonic supersolid phase in anisotropic semiconductors with screened interactions, expanding understanding of exciton condensate crystallization patterns.

Findings

Stripe-shaped exciton crystal phase identified in anisotropic semiconductors.

Conditions for coexistence of excitonic superfluidity and crystallization established.

Screened interactions lead to non-hexagonal, stripe-like lattice structures.

Abstract

Within the Gross-Pitaevskii framework, we reveal the emergence of a crystallized phase of an exciton condensate in an atomically-thin anisotropic semiconductor, where screening of exciton-exciton interactions is introduced by a proximal doped graphene layer. While such screened interactions are expected to yield a hexagonal crystal lattice in the excitonic condensate in isotropic semiconductor quantum wells [see e.g. Phys. Rev. Lett. \textbf{108}, 060401 (2012)], here we show that for atomically thin semiconductors with strong electronic anisotropy, such as few-layer black phosphorus, the crystallized exciton phase acquires a parallel stripe structure - unanticipated to date. The optimal conditions for the emergence of this phase, as well as for its coexistence with excitonic superfluidity in a striped supersolid phase, are identified.