Magnetic properties of a random anisotropy model with both ferromagnetic and antiferromagnetic exchange coupling

Abstract

The model of Harris et al. for random magnetic anisotropy is examined for the case of nearest neighbour antiferromagnetic and next-nearest neighbour ferromagnetic exchange coupling. Initial magnetization curves, critical fields for the metamagnetic transition, and hysteresis loops were obtained for a variety of parameters using the molecular field approximation and were compared with previous work. It is shown that the metamagnetic transition becomes a discontinuous transition and that the hysteresis loops change their shape considerably in the presence of ferromagnetic exchange. The results are discussed in the light of experimental work.