EFFECT OF A RANDOM CRYSTALLINE FIELD ON THE CURIE-TEMPERATURE OF AN ANISOTROPIC CRYSTALLINE FERROMAGNET

We examine how substitution of nonmagnetic atoms of one species by ano ther that leads to the emergence of a random crystalline field affects the Curie temperature T-C of an anisotropic crystalline ferromagnet. We study the case of low concentrations, in which individual substitut ional impurities create isolated clusters of perturbed magnetic ions w ith additional easy- or hard-magnetization axes. Finally, we analyze t he various sign relations among the parameters D and d of regular and impurity second-order anisotropies with Kramers (J = 1) and non-Kramer s (J = 3/2) angular momenta, and show that usually the effects of a ra ndom crystalline field lower the Curie temperature as the concentratio n of the nonmagnetic impurity atoms increases. (C) 1997 American Insti tute of Physics.