Linear chain approximation for an anisotropic cubic spin-one Ising model

Abstract

The magnetization of an anisotropic cubic spin-one Ising model with single-ion anisotropy is studied using a linear chain approximation. In particular, for several ratios, η, between the interchain and intrachain exchange interactions the critical temperatures of the second and first order phase transitions are computed as a function of the single-ion anisotropy strength. The virtue of the method is that it removes some of the unsatisfactory features found in molecular field theory when the interchain interactions are weak. In the limit η→0 the results are of course exact, and thus the method is particulary well-suited to the study of quasi one-dimentional systems. Moreover, comparison of the results with those of molecular field theory, pair model and constant coupling approximations, high temperatures series expansion and other methods show that the results are reasonable over a large range of η, even up to the isotropic limit.