Collapse-Like Decrease of RKKY Interaction and Kondo Effect in Heavy Fermion Compounds (Ce1-XGdX)Ni (0.03≤X ≤0.20)

Small amounts of Ce were substituted by Gd and the (Ce-Gd)Ni heavy fermion compounds were investigated in detail from viewpoint of magnetism in Gd-poor region between 3 at% and 20 at%. Magnetizations showed peculiar linear relationship as a function temperature and were sensitive to the applied magnetic field in common. These characteristic natures were analyzes employing molecular field analysis by changing three exchange interaction energies, JGd-Gd, JGd-Ni and JNi-Ni. The unique solution for the linear relationship in the temperature dependence of magnetization M(T) was found to be attributed to the collapselike decrease of JGd-Gd and the decrease of JGd-Gd can explain the sensitivity to applied magnetic field. However this peculiar decrease of JGd-Gd did not effect on the inverse susceptibilities above the Curie temperatures and the ?-1(T) behaved normally as ferri-magnet.