Chapter 11 Kondo effect: Alloys and compounds

Abstract

The chapter discusses the Kondo effect. The interaction between impurity ions with partially filled d or f electron shells and the conduction electrons of a metallic host can lead to variations in certain physical properties with temperature and magnetic field that have come to be associated with the “Kondo effect.” In zero magnetic field, these temperature dependent anomalies in the physical properties scale with a characteristic temperature TK, the Kondo temperature, above which the matrix impurity system behaves magnetically and below which the matrix-impurity system behaves nonmagnetically. The physical properties that exhibit anomalies attributable to the Kondo effect include the electrical resistivity, magnetic susceptibility, thermoelectric power, specific heat; and, in systems where appropriate, superconducting properties such as the critical temperature Tc and the jump in specific heat that occurs at Tc. Because of the wide range of magnetic character displayed by the lanthanide metallic systems reviewed in the chapter, they provide a rich testing ground for the concepts and theories that have been advanced to account for Kondo-like anomalies in the physical properties of these systems. The chapter briefly discusses a number of models, which have been proposed to describe the systems that exhibit Kondo-like behavior in their physical properties.