The dynamical frustration of interlayer excitons delocalizing in bilayer quantum antiferromagnets

¹ Institute-Lorentz for Theoretical Physics, Leiden University - P.O. Box 9506, NL-2300 RA Leiden, The Netherlands, EU
² Institute for Advanced Study, Tsinghua University - Beijing, 100084, China
³ Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente P.O. Box 217, NL-7500 AE Enschede, The Netherlands, EU

^a rademaker@lorentz.leidenuniv.nl

Received: 17 August 2011
Accepted: 5 December 2011

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.