The magnetic susceptibility (χ) of polycrystalline samples of RGa 2, R=Ce, Pr, Nd, Gd, Tb, Dy, Ho, and Er, has been measured at low field, from 1.5 K to 300 K. The magnetization of these samples also has been measured up to 80 kOe at low temperatures. Antiferromagnetic behavior was observed for all the samples with Neel temperatures (TN) ranging from about 4.1 K for CeGa2 to about 14.8 K for TbGa2. Curie-Weiss fits to the high-temperature χ (T) data led to effective moments in good agreement with those expected for R3+ ions. The paramagnetic Weiss temperatures cannot be reconciled with the de Gennes theory based on free electron coupling of the R spins via the RKKY interaction. Electrical resistivity of selected polycrystalline samples has been measured, and the effects of spin-disorder scattering observed below TN. CeGa 2 shows no evidence of Kondo behavior. Magnetization measurements for the polycrystalline samples show metamagnetic phase transitions when the antiferromagnetic R-R interactions are overcome. Measurements on a HoGa 2 single crystal show that the  direction is the easy direction.
ASJC Scopus subject areas
- Physics and Astronomy(all)