Specific heat, susceptibility, magnetotransport and thermoelectric power of the Kondo alloys (Ce_1-xLa_x)Cu₅In

The influence of substituting Ce with La in the Kondo compound CeCu₅In has been investigated using x-ray diffraction, specific heat (C_p), electrical resistivity (ρ(T)), magnetoresistivity (MR) and thermoelectric power (TEP) measurements. C_p of CeCu₅In and the (Ce_1-xLa_x)Cu₅In alloys shows enhanced values at low temperatures. Between 10 and 20 K the equation C_p/T = γ^conv + βT² fits the data for all alloys with γ^conv scaling linearly with Ce concentration. Below 10 K a pronounced upturn in C_p values occurs. Susceptibility data above 100 K follow the Curie-Weiss relation and give effective moment μ_eff values in fair agreement with that of a Ce³⁺-ion. The ρ(T) studies illustrate the evolution from Kondo lattice to single-ion Kondo behaviour with increase in La content in the (Ce_1-xLa_x)Cu₅In alloy series. MR measurements on Ce dilute alloys are interpreted within the single-ion Bethe ansatz description and values of the Kondo temperature T_K are calculated. A compressible Kondo lattice model has been used to describe the decrease in T_K and in T_m^ρ (the temperature at which a maximum in ρ(T) occurs for the coherent dense Kondo alloys) with decrease in Ce concentration for these alloys. The TEP is positive and shows a maximum at approximately 45 K for several investigated (Ce_1-xLa_x)Cu₅In alloys.