Magnetic Studies of Gadolinium Compounds with the CsCl Structure

Abstract

The dominant interaction in rare-earth compounds with the CsCl structure is the Ruderman-Kittel-Yosida exchange due to polarization of the conduction electrons. In the rare-earth systems RA (where A=Ag, Cu, Zn, Cd, In), it was found that RAg and RCu are antiferromagnetic; RZn and RCd are ferromagnetic; RIn is antiferromagnetic. This change in magnetic properties can be attributed to the variation of conduction-electron concentration. We have prepared the ternary solid solutions: Gd(ZnxAg1−x), Gd(ZnxIn1−x), Gd(ZnxCu1−x), and (Gd1.2Cd)x(GdAg)1−x [0≦x≦1] to study the effect of changes in electron concentration on the magnetic properties of these materials. The Curie temperature of GdZn and Gd1.2Cd are about 280°K; the Néel temperatures of GdAg, GdCu, and GdIn are reported to be 145°, 41°, and 28°K. The change of the paramagnetic Curie temperatures in the Gd(ZnxAg1−x) and Gd(ZnxIn1−x) systems is in qualitative agreement with the Gd(AgxIn1−x) system as reported by Sekizawa et al. and is consistent with theoretical expectations, assuming that Ag, Zn, and In give one, two, and three conduction electrons. In the composition region 0.4≦x≦1, both systems are ferromagnetic and the Curie temperature decreases as x decreases. At x=0.2 the compounds are probably antiferromagnetic. The total magnetic moment also diminishes as x decreases, in a field of 4 kOe. We expect the total moment to remain constant at 7 μB/Gd for the ferromagnetic compounds at higher fields. The Gd(ZnxCu1−x) and (Gd1.2Cd)x(GdAg)1−x systems show the same trend.