THICKNESS DEPENDENCE OF THE KONDO EFFECT IN AUFE FILMS

We have studied the Kondo effect in thin films of AuFe, through measurements of the temperature dependence of the resistivity, DELTA-p(T). At low temperatures, we find DELTA-p = Bln(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.