Magnetic properties of rare--Earth--Iron intermetallic compounds

Curie points, the temperature dependence of the high-field magnetization below room temperature, saturation moments, and densities are reported for the most iron-rich compounds in the rare earth-iron systems. The heavy rare earth compounds have the composition A2Fe14and the hexagonal Th2Ni17-type structure, while the light rare earths have the stoichiometry AFe7and a modified rhombohedral Th2Zn17structure. From the saturation of Y2Fe17and Lu2Fe17, an iron moment of2.0μBis calculated. In these two compounds and in CeFe7, PrFe7, and, perhaps, NdFe7, all atomic moments couple ferromagnetically, while for Gd2Fe17through Tm2-Fe17the magnetizations of the rare earth and iron sublattices subtract. Curie temperatures range from -180°C (CeFe7) through a peak of +186°C (Gd2Fe17) to -41°C (Tm2Fe17). This suggests that two exchange mechanisms are active which make comparable contributions to the interaction energy: direct exchange between Fe atoms and indirect coupling via conduction electrons between iron and the rare earth atoms.