WEAK ANISOTROPIC IMPURITY SCATTERING IN UNCONVENTIONAL SUPERCONDUCTORS

The effect of weak anisotropic (momentum-dependent) impurity scatterin g in unconventional superconductors has been investigated. It is shown that the anisotropic scattering can lead either to a small reduction or a small enhancement of the isotropic pair-breaking effect. The infl uence of the anisotropy of the scattering potential becomes significan t for the order parameters with large Fermi surface average values. In that case an unexpected enhancement (up to similar to 10%) of the cri tical temperature T-c over the critical temperature in the absence of impurities T-c0 is predicted for a small impurity concentration. Copyr ight (C) 1996 Elsevier Science Ltd.