The dynamical frustration of interlayer excitons delocalizing in bilayer quantum antiferromagnets

TL;DR

This paper investigates how interlayer excitons in bilayer quantum antiferromagnets become delocalized due to strong coupling with the spin system, revealing confinement physics similar to Ising models and predicting observable spectral features.

Contribution

It introduces a self-consistent Born approximation analysis of exciton delocalization in bilayer antiferromagnets, highlighting enhanced coupling effects and confinement physics.

Findings

Strong exciton-spin coupling mimics confinement physics.

Ladder spectrum should be observable in bilayer cuprates.

Finite exciton density may lead to complex physical behaviors.

Abstract

Using the self-consistent Born approximation we study the delocalization of interlayer excitons in the bilayer Heisenberg quantum antiferromagnet. Under realistic conditions we find that the coupling between the exciton motion and the spin system is strongly enhanced as compared to the case of a single carrier, to a degree that it mimics the confinement physics of carriers in Ising spin systems. We predict that the "ladder spectrum" associated with this confinement physics should be visible in the c-axis exciton spectra of insulating bilayer cuprates such as YBa2Cu3O6. Our discovery indicates that finite density systems of such excitons should show very rich physical behavior.