Competition between the Kondo effect and exchange interactions in theCeNixPt1−xcompounds

Abstract

Magnetic and resistivity measurements performed on the $\mathrm{Ce}{\mathrm{Ni}}_x{\mathrm{Pt}}_{1-x}$ compounds show that this system is one of the best examples of a ferromagnetic dense Kondo system in which Ruderman-Kittel-Kasuya-Yosida exchange interactions compete with the Kondo effect. The variations of the Curie temperature $T_C$ and of the Kondo temperature $T_K$ as a function of the Ni content are in qualitative agreement with those calculated as a function of the product $\left|\Gamma n\right(E_F\left)\right|$ in the Kondo lattice model, where $\Gamma (<0)$ is the coupling constant between the $4f$ shell and the conduction band. The increase of $\left|\Gamma n\right(E_F\left)\right|$ as a function of the Ni content is suggested to be mainly due to the decrease of the separation between the $f$ level and the Fermi level.