Dense kondo effect in caged compound CeRu₂Zn₂₀

We prepared single crystals of the caged compound CeRu₂Zn ₂₀ by the flux method, and measured the magnetization, magnetic susceptibility, specific heat, and electrical resistivity. The lattice constant measured at room temperature suggests that the Ce ion is trivalent in this compound. The temperature dependence of magnetic susceptibility obeys the Curie-Weiss law with the effective Bohr magneton of Ce³⁺ at high temperatures. However, at low temperatures, CeRu₂Zn₂₀ indicates no phase transition down to 2K and shows typical behaviors of a heavy Fermion system; the enhanced magnetic susceptibility Χ₀, the enhanced electronic specific-heat coefficient γ₀, and the electrical resistivity with the temperature dependence of AT2, although these parameters somewhat depend on samples. The Wilson ratio RW of Χ₀=γ₀ is approximately 2, which does not depend on samples. A=γ₀ is plotted on the line of N = 2 in the new Kadowaki-Woods plots. The Kondo temperature TK is roughly estimated from the present experiments; it ranges from 25 to 38K depending on samples. These characteristics are typical of dense Kondo compounds.