Random Kondo alloys investigated with the coherent potential approximation

The interplay between the Kondo effect and disorder is studied. This is done by applying a matrix coherent potential approximation and treating the Kondo interaction on a mean-field level. The resulting equations are shown to agree with those derived by the dynamical mean-field theory. By applying the formalism to a Bethe tree structure with infinite coordination, the effects of diagonal and off-diagonal disorder are studied. Special attention is paid to the behavior of the Kondo and the Fermi-liquid temperature as function of disorder and concentration of the Kondo ions. The nonmonotonous dependence of these quantities is discussed.