A.c. susceptibility studies of the UM 2Ge 2, TbM 2Ge 2, and HoM 2Ge 2 compounds (M = Co, Ni, Cu)

Abstract

Polycrystalline samples of the compounds UM 2Ge 2, TbM 2Ge 2, and HoM 2Ge 2 (M = Co, Ni, Cu) were studied by a.c. susceptibility measurements from room temperature (RT) (295 K) to 80 K. The paramagnetic Curie temperature θ and effective magnetic moment μ eff were determined. The variations in magnetic parameters with M in the U and Tb compounds are similar: T N, RT χ M, and μ eff decrease and θ increases as M varies from Co to Cu. In the Ho compounds these parameters are quite constant, and the μ eff values are close to the free Ho 3+ ion value (4f 10 configuration). The higher μ eff values in UCo 2Ge 2 (compared with 5f 1 to 5f 4) and TbCo 2Ge 2 (compared with 4f 8) are attributed to paramagnetic cobalt moments that do not order, and such moments decrease for nickel and disappear for copper.