Thickness dependence of the Kondo effect in AuFe films

Abstract

We have studied the Kondo effect in thin films of AuFe, through measurements of the temperature dependence of the resistivity, \ensuremath{\Delta}\ensuremath{\rho}(T). At low temperatures, we find \ensuremath{\Delta}\ensuremath{\rho}=-B ln(T), as expected for the Kondo effect. We have also found that the factor B becomes smaller as the film thickness is reduced. This result is discussed in terms of the effect of the film thickness on the conduction-electron screening cloud which forms around the magnetic impurities, and the associated crossover from three- to two-dimensional behavior. Studies of bilayer films, which seem to support this interpretation, are also described.