Observation of RKKY-Kondo Competition and Non-Fermi-Liquid Behavior in the Intermetallic Compound Series Ce(Cu1−xNix)Si2

We study Kondo-RKKY competition in the intermetallic compound series Ce(Cu 1− x Ni x )Si 2 ( x =0, 0.2, 0.4, 0.6, 0.8, 1.0) by performing X-ray diffraction, electrical resistivity, magnetic susceptibility measurements and Ce-L III -edge X-ray absorption spectra. The results reveal that RKKY interaction dominates and leads to spin-glass behavior at the Cu rich end. For the Ni rich end the Kondo effect prevails and drives the system towards an intermediate-valence regime with nearly quenched magnetism. According to the experimental result, we are able to obtain a phase diagram similar to Theumann’s theoretical model. This work also observed non-Fermi-liquid behavior from the ρ ( T ) and χ ( T ) measurements at x =0.6, indicating this series to lie in the vicinity of a quantum critical point at this content.