Abstract
The ordering in the Cu-O basal plane of is investigated as a function of oxygen content and temperature. A phase diagram is calculated by application of the cluster variation method to an asymmetric two-dimensional Ising model. The interaction parameters selected guarantee the stability of the experimentally observed double-cell structure around z=6.5. The transition temperatures at various oxygen partial pressures are in good agreement with experiment. The pair probabilities along the Cu-O chains show a plateau with varying oxygen concentration, not unlike the dependence of on oxygen content.
- Received 29 December 1987
DOI:https://doi.org/10.1103/PhysRevLett.60.1065
©1988 American Physical Society