of T c by nonmagnetic as well as by magnetic impurities. We report measurements of
chemical composition and of transport properties in the same single crystals of Sr 2 RuO 4
which show that nonmagnetic impurities destroy superconductivity when the residual
resistivity exceeds 1 μ Ω cm, ie, when the carrier mean free path falls below the
superconducting coherence length. This behavior strongly supports models of non-s-wave …