Phase Diagrams of Rare-Earth Ferrimagnets with Surface Anisotropy near Their Points of Compensation

A theoretical model is proposed for calculating the H‒T phase diagrams of a rare-earth ferrimagnet. The model considers the effects of each magnetic sublattice and the induced surface anisotropy. The magnetic phase diagrams are calculated numerically. Surface anisotropy blurs the lines of the second-order phase transition between the collinear and angular phases, the displacement of the tricritical point, and the possible formation of new phase transition lines.