An adequate interpretation of charge transport for a dilute La 1−xCe xB 6 system

Abstract

Precision measurements of charge transport characteristics (resistivity and Seebeck coefficient) have been carried out on the high quality single crystals of the so-called dilute Kondo system La 1− x Ce x B 6 ( x⩽0.1) in a wide temperature range 1.8–300 K. At low temperatures, it was shown that instead of Kondo-type logarithmic contribution to resistivity Δ ρ∼−ln T the magnetic component obeys the power law Δ ρ∼ T −a , which corresponds to the regime of weak localization of charge carriers with the critical exponent values a=0.47–0.49 for x⩽0.1. An asymptotic behavior of Seebeck coefficient S∼−ln T found for these dilute magnetic compounds at intermediate temperatures is compared with S( T) dependence observed for the dense system CeB 6. The data obtained for La 1− x Ce x B 6 are analyzed in terms of Kondo-impurity model and alternative spin-polaron approach.