Evolution from intermediate-valence to antiferromagnetic Kondo-lattice behavior in CeNi(GexSi1−x)2

A cerium-based intermetallic compound series CeNi(GexSi1−x)2 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) were synthesized. Among the compounds, CeNiSi2 is an intermediate-valence compound, while CeNiGe2 is a Kondo-lattice with a two-step antiferromagnetic phase transition. In this work, X-ray powder diffraction, transport, magnetic and thermal measurements, as well as Ce-LIII spectroscopy are presented in order to study the crossover from non-magnetic intermediate-valance regime to antiferromagnetic Kondo-lattice regime in the CeNi(GexSi1−x)2 series. Increasing Ge concentration will depress the hybridization between 4f electrons and conducting electrons and enhance the RKKY interaction, which eventually drive the system to a magnetically ordered state.