EFFECT OF ANISOTROPIC IMPURITY SCATTERING IN SUPERCONDUCTORS

We discuss the weak-coupling BCS theory of a superconductor with impur ities, accounting for their anisotropic momentum-dependent potential. The impurity scattering process is considered in the t-matrix approxim ation and its influence on the superconducting critical temperature T- c is studied in the Born and unitary limit for a d(x2-y2)- and (d(x2-y 2)+s)-wave superconductors. We observe a significant dependence of the pair-breaking strength on the symmetry of the scattering potential an d classify the impurity potentials according to their ability to alter T-c. A good agreement with the experimental data for Zn doping and ox ygen irradiation in the overdoped cuprates is found. [S0163-1829(98)05 542-8].