A Computational Study of Oxygen Ordering in YBa₂Cu₃O_z and its Relation to Superconductivity

Abstract An ab initio model to study oxygen ordering in the high temperature superconductor YBa2Cu3Oz is presented. The phase diagram computed with this model contains several ordered structures and is in excellent agreement with the known experimental information. At high temperature, an orthorhombic structure transforms by a second order reaction into a tetragonal structure. At low temperature, a branching algorithm generates an infinity of ordered structures all consisting of long O–Cu–O chains. By looking at the kinetic evolution of quenched samples in a Monte Carlo simulation it was possible to clarify how annealing of the material can influence its superconducting transition temperature.