High-temperature series expansion for an easy-axis ferromagnet with exchange and dipolar interactions

Abstract

High-temperature series expansions for the magnetic susceptibility and the specific heat have been developed for spin-one ferromagnetic systems with Heisenberg exchange interactions, magnetic dipole-dipole interactions, and single-ion easy-axis anisotropy. The results are valid for arbitrary strength of the single-ion anisotropy and therefore have broader application than Marquard's results. We have obtained the first four terms in each high-temperature series. Effects of the dipolar interactions and the uniaxial anisotropy on ferromagnetic ordering are also discussed.