LOCAL PERTURBATION OF AN ORDER-PARAMETER INDUCED BY AN IMPURITY IN ANISOTROPIC SUPERCONDUCTORS

We compute the local variation of order parameter induced by an impurity for the two-dimensional order parameters of the general non-s-wave gap as well as an anisotropic s-wave gap, while taking into account the Born and unitarity limits of impurity scattering at all temperatures. The anisotropy of the perturbed gap is determined by the symmetry of the underlying order parameters. The perturbation for the anisotropic s-wave gap is much weaker than the non-s-wave gaps. © 1995 The American Physical Society.