Magnetic Order in Rare-Earth Intermetallic Compounds

Abstract

Neutron diffraction measurements were made on a series of rare-earth intermetallic compounds to determine the type of magnetic order and its relationship to the number of valence electrons in the system. The compounds studied included TbCu, TbZn, TbGa, TbAg, TbHg, and TbIn. The compounds with Cu, Zn, Ag, and Hg were found to have the CsCl-type structure, TbGa the CrB-type structure, and TbIn a complex tetragonal unit cell. TbGa is ferromagnetic with a Curie temperature of 155°K, while TbIn is antiferromagnetic below 190°K. For the compounds with the CsCl structures, TbCu and TbAg are antiferromagnetic with Néel temperatures of 115 and 100°K, while TbZn and the TbHg are ferromagnetic below 160 and 80°K, respectively. This difference is magnetic behavior of the compounds with group Ib and IIb metals must be associated with the number of valence electrons rather than with interatomic separations because the lattice constants of the two groups overlap.