A series study of a mixed-spin ferrimagnetic Ising model

Abstract

We use both high- and low-temperature series expansions to investigate the phase diagram of a ferrimagneticmixed-spin S = (1/2,1) Ising model on the square lattice, including an on-site anisotropy term on theS = 1 sites. Evidence is found for a first-order transition for large negative anisotropy, andhence for the existence of a tricritical point. The model, with nearest neighbourinteractions only, does not appear to have a ferrimagnetic compensation point.