MICROWAVE PROPERTIES OF (PRXY1-X)BA2CU3O7-DELTA - INFLUENCE OF MAGNETIC SCATTERING

We report measurements of the surface impedance Z(s) = R-s + iX(s) of( PrxY1-x)Ba2Cu3O7-delta , (x = 0, 0.15, 0.23, 0.3, 0.4, 0.5). Increasin g Pr concentration leads to some striking results not observed in samp les doped by non-magnetic constituents. The three principal features o f the R-s(T) data - multiple structure in the transition, a high resid ual resistance and, at high Pr concentrations, an upturn of the low T data - are all characteristic of the influence of magnetic scattering on superconductivity, and appear to be common to materials where magne tism and superconductivity coexist. The low T behavior of lambda(T) ap pears to change from T to T-4 at large Pr doping, unlike that reported for Ni and Zn substitutions, and is further evidence of the influence of magnetic pair breaking of the Pr. (C) 1997 Elsevier Science B.V.