INTERLAYER PAIRING IN HIGH-TEMPERATURE SUPERCONDUCTORS - EFFECT OF NONMAGNETIC IMPURITIES

The influence of impurity scattering is studied theoretically in a two-layer model for the high-Tc superconductor Y1Ba2Cu3O7-δ with intra- and inter-layer pairing. Two types of impurities are considered: (I) impurities which conserve the reflection symmetry of the two layers and (II) impurities which break it. Impurities of type (I) have no influence on the critical temperature. Type (II) impurities have strong influence on Tc as well as on Hc2 if there is a pairing interaction between carriers of different layers. The treatment of type (II) impurities is generalized to a periodic layer model appropriate for La2-xBaxCuO4. Available experiments on impurities in Y1Ba2Cu3O7-δ and La2-xBaxCuO4 are interpreted with our theory. © 1990 Springer-Verlag.