Phase transitions in ordered and disordered ferrimagnets. I. Correlated molecular field theory and Monte Carlo simulations

Abstract

AbstractThe uniform and the staggered paramagnetic zero‐field susceptibility χ of ordered and disordered ferrimagnets are calculated by means of the correlated molecular field theory and by Monte‐Carlo computer simulations. The results are similar to the case of disordered ferromagnets: site disorder gives rise to a wide transition regime from the asymptotic critical behaviour to the mean‐field behaviour, with strong upward curvature of the plot χ−1(T). In contrast, bond disorder has only a weak influence on χ−1(T). For the ordered S = 1/2 / 1 Ising ferrimagnet on a simple cubic lattice the Monte Carlo simulation yields a critical temperature consistent with that found by high‐temperature series expansons of Schofield and Bowers.