Coherent Kondo State in a Dense Kondo Substance: Ce_<i>x</i>La_1-<i>x</i>Cu₆

Abstract

The electrical resistivity, magnetoresistance and magnetic susceptibility of single crystalline Ce x La 1- x Cu 6 ( x =0-1) have been measured down to mK region. As the Ce concentration is increased, the consecutive change from the dilute (incoherent) Kondo regime to the Kondo lattice (coherent) regime is observed. The characteristic features in the coherent Kondo regime are clearly observed in the resistivity and the magnetoresistance above x =0.7. The low temperature resistivity in Ce x La 1- x Cu 6 shows a T 2 dependence and the residual resistivity follows the Nordheim law. As for the coherence effect in CeCu 6 , the resistivity follows a T 2 dependence below 0.1 K, the magnetoresistance changes from negative to positive below about 0.15 K within applied magnetic fields and the susceptibility shows an enhanced Pauli paramagnetism below 1 K.