SIZE DEPENDENCE OF KONDO SCATTERING IN POINT CONTACTS - FE IMPURITIESIN CU

The size dependence of electron-spin scattering is investigated by mea ns of point-contact spectroscopy of the Kondo alloy CuFe(0.1 at. %). W e can study junctions of various sizes (d similar or equal to=1.5-35 n m) using mechanically controllable break junctions (MCB's). In a previ ous MCB study of the Kondo alloy CuMn the Kondo temperature T-K was ob served to increase by many orders of magnitude in this range of contac t sizes. For CuFe we also find an increase of T-K, but only by a facto r similar to 2. This observation is in qualitative agreement with the theory recently proposed by Zarand and Udvardi.