LOW-TEMPERATURE EXCITATIONS IN CERU2SI2-XGEX ALLOYS

Alloys in the series CeRu2Si2-xGex have been studied by inelastic neut ron scattering. The high temperature quasielastic response is consiste nt with a smooth decrease in the 4f-conduction electron hybridisation with increasing x. The linewidths are strongly modulated with wavevect or Q, indicating the presence of strong RKKY interactions. The single ion component of the dynamical response shows scaling with x and T in good agreement with standard Kondo theory. In the ordered state, for x approximate to 1, the longitudinal spin fluctuations are characterise d by an inelastic peak. The strength of this inelastic response decrea ses with increasing x, as the exchange field wins over the Kondo scree ning. The neutron cross-sections are well described by a simple ansatz in which the screened state of the 4f electrons is represented by a p air of singlets separated by an energy of order k(B)T(K).