Magnetic properties of Gd(Fesub(y)Alsub(1-y))3 and (Gdsub(x)Ysub(1-x))Fe3 compounds

The results of magnetic measurements performed on Gd(Fesub(y)Alsub(1-y))3 and (Gdsub(x)Ysub(1-x))Fe3 compounds over the temperature range 4.2-1300 K are reported. For x and y >= 0.2 the compounds are ferrimagnetically ordered. In this case, the reciprocal susceptibility chi-1 follows a Neel-type hyperbolic law. The YFe3 compound is ferromagnetic and chi-1 obeys a Curie-Weiss behaviour. Both mean iron moments determined from saturation measurements and Curie constants decrease, but only slowly, by increasing the aluminium or yttrium content. The composition dependence of the iron moments is ascribed to the reduced exchange splittings of Fe 3d states. The electron paramagnetic resonance studies on ferrimagnetic compounds show that the g values and the slope of the linewidth are temperature dependent. The data are analysed in a model which uses the molecular field approximation. (author)