From microscopic description to statistical mechanics of Cu-O chain fragments in the high-Tc superconductors REBa_2Cu_3O_{6+x}

TL;DR

This paper develops a statistical mechanics model for Cu-O chain fragments in high-Tc superconductors, linking microscopic Emery model details to macroscopic properties affecting superconductivity.

Contribution

It introduces an extended ASYNNNI model based on the Emery model to describe CuO_x planes, analyzed with Monte Carlo simulations.

Findings

Charge transfer to CuO2 planes quantified

Concentration of Cu ions with different coordination analyzed

Model results compared successfully with experimental data

Abstract

The oxygen deficient CuO_x planes of the high-Tc superconductors REBa_2Cu_3O_{6+x} (RE denotes a rare-earth atom or yttrium) are studied. Starting from the Emery model for the Cu-O chain fragments, an extended ASYNNNI model is proposed to describe the statistical mechanics of the CuO_x planes. The model is analysed by using Monte Carlo techniques, computing especially the charge transfer to the CuO$_2$ planes regulating the high-Tc superconductivity, and the concentration of differently coordinated Cu ions.Results are compared to experimental data for various RE cases.