Instability of charge ordered states in doped antiferromagnets

TL;DR

This paper investigates how quantum zero point spin wave energy modifications induce attractive interactions between holes in doped antiferromagnets, leading to potential instability of charge-ordered states in dilute doping conditions.

Contribution

It demonstrates that zero point energy effects cause attractive interactions between holes, which can destabilize charge order in doped antiferromagnets, a novel insight into their quantum behavior.

Findings

Interaction is uniformly attractive and decays as r^{-2d+1} in d dimensions.

For stripe configurations, the interaction per unit area decays as r^{-d}.

Charge-ordered states become unstable without Coulomb repulsion at low doping.

Abstract

We analyze the induced interactions between localized holes in weakly-doped Heisenberg antiferromagnets due to the modification of the quantum zero point spin wave energy; i.e. the analogue of the Casimir effect. We show that this interaction is uniformly attractive and falls off as r^{-2 d+1} in d dimensions. For ``stripes'', i.e parallel (d-1)-dimensional hypersurfaces of localized holes, the interaction energy per unit hyperarea is attractive and falls, generically, like r^{-d}. We argue that, in the absence of a long-range Coulomb repulsion between holes, this interaction leads to an instability of any charge-ordered state in the dilute doping limit.