Flexural deformations and collapse of bilayer two-dimensional crystals by interlayer exciton

TL;DR

This paper develops a theory describing how interlayer excitons in bilayer 2D crystals cause flexural deformations and collapse, influenced by tension and nonlinear effects, impacting exciton properties and stability.

Contribution

It introduces a comprehensive model of interlayer exciton-polaron formation, including effects of tension, nonlinearity, and collapse criteria in bilayer 2D materials.

Findings

Tension suppresses polaron formation in weak and strong coupling regimes.

Nonlinear interactions lead to a criterion for layer sticking and exciton collapse.

Flexural deformations significantly influence exciton properties in bilayer crystals.

Abstract

We develop a consistent theory of the interlayer exciton-polaron formed in atomically-thin bilayers. Coulomb attraction between an electron and a hole situated in the different layers results in their flexural deformation and provides an efficient mechanism of the exciton coupling with flexural phonons. We study the effect of layers tension on the polaron binding energy and effective mass leading to suppression of polaron formation by the tension both in the weak and strong coupling regimes. We also consider the role of the nonlinearity related to the interaction between the out- and in-plane lattice displacements and obtain the criterion of the layer sticking, where the exciton collapses, due to the Coulomb attraction between the charge carriers.