FINITE-RANGE SCATTERING OF NI AND ZN IMPURITIES IN Y-123 THIN-FILMS

We investigated YBa2(Cu1-xMz)(3)O7-delta (M=Ni,Zn) thin films and dete rmined the decrease of T-c and the increase of residual resistivity du e to Cu-site substitution, taking into account the CuO-chain contribut ions to the total conductivity. Although Zn suppresses T-c stronger th an Ni by a factor of 2.3 the increase of resistivity differs only slig htly. Furthermore the observed resistivities are too high to be explai ned within scattering from point-like defects. To reconcile these cont radictions, we assumed finite size scattering potentials, which lead t o scattering phase shifts delta(1) of higher angular momentum l > 0. T -c-suppression is discussed qualitatively within this picture.