Effects of Magnetic and Non-Magnetic Impurities on Anisotropic Singlet Superconductors

Abstract
We examine effects of magnetic and non-magnetic impurities on superconductors with anisotropic Cooper pairs of spin-singlet and calculate the tunneling density of states. When the Cooper pair has no component with s-symmetry, magnetic impurities result in the same pair-breaking effect as non-magnetic ones, which is weaker than the usual time-reversal symmetry breaking. The recently discovered high T c magnetic superconducting oxides, R-Ba-Cu-O with R being rare-earth ions, are discussed in the light of the present theory.