Uniaxial S=1 antiferromagnet

The statistical mechanics of uniaxial S=1 antiferromagnets with both intrasublattice and intersublattice exchanges is considered in both antiferromagnetic and paramagnetic phases, using the standard basis operator method introduced by Haley and Erdos (see abstr. A19483 of 1972). In this Green function technique, the exchange terms are treated in the random phase approximation, while the single-ion anisotropy is treated exactly. Particular emphasis is given to quantitative calculations of sublattice magnetization, Neel temperatures and perpendicular susceptibility. In some limiting cases such as low anisotropy, high temperature and vanishing intrasublattice exchange, the results are in agreement with those obtained by other theories.