Competition between the Kondo effect and exchange interactions in the systemCeSix

Precision electrical resistivity measurements on twelve alloys in the series ${\mathrm{CeSi}}_{\mathrm{x}}$ (1.60≤x≤1.90) reflect the smooth progression from a magnetically ordered dense Kondo system (x≤1.85) to compositions where the conventional single-impurity Kondo effect dominates the exchange interaction, resulting in a ground state which is not magnetically ordered. The variations of the Kondo temperature and the magnetic ordering temperature are determined as a function of Si content and found to agree well with the theoretical Kondo-lattice model.