Extended random phase approximation for layered copper oxides antiferromagnets

The role of interlayer coupling constant on the Neel temperature of layered copper oxides and other magnetic properties have been studied. The theoretical framework is based on anisotropic Heisenberg model and the two sublattice approach. The higher-order Green functions are decoupled using the second random phase approximation. The Green's function related to the localized spin correlation functions has been exploited. A self consistent expression for the sublattice magnetization and a corrected form for the Noel temperature are obtained. The free-spin-wave results are obtained under a specific approximation. The theoretical results are compared with that of the random phase approximation and existing experimental results.