Detailed investigation of thermal and electron transport properties in strongly correlated compound Ce₆Pd₁₂In₅ and its nonmagnetic analog La₆Pd₁₂In₅

An in-depth study of thermal and electron transport properties including thermal conductivity κ(T), thermoelectric power S(T), and electrical resistivity ρ(T) of the heavy fermion Kondo lattice Ce₆Pd₁₂In₅ and its nonmagnetic reference compound La₆Pd₁₂In₅ is presented. The absolute κ(T) value of Ce₆Pd₁₂In₅ is smaller that than of La₆Pd₁₂In₅, which indicates that conduction electron-4f electron scattering has a large impact on the reduction of thermal conductivity. The isolated 4f electron contributions to the electrical resistivity ρ_4f(T), electronic thermal resistivity displayed in the form W_el,4f(T)·T, and thermoelectric power S_4f(T) reveal a low- and high-temperature -lnT behaviour characteristic of Kondo systems with strong crystal-electric field (CEF) interactions. The analysis of phonon scattering processes of lattice thermal conductivity κ_ph(T) in (Ce, La)₆Pd₁₂In₅ was performed over the whole accessible temperature range according to the Callaway model. In the scope of a theoretical approach based on the perturbation type calculation, we were able to describe our experimental data of ρ_4f(T) and W_el,4f(T)·T by using the model incorporating simultaneously the Kondo effect in the presence of the CEF splitting, as it is foreseen in the framework of the Cornut-Coqblin and Bhattacharjee-Coqblin theory. Considering the fact that there are not many cases of similar studies at all, we also show the numerical calculations of temperature-dependent behaviour of spin-disorder resistivity ρ_s(T), magnetic resistivity ρ_4f(T), and occupation number 'N_i' due to the various types of degeneracy of the ground state multiplet of Ce³⁺ (J = 5/2).