Microwave properties of $(P{r}_x{Y}_{1-x})B{a}_{2}C{u}_3{O}_{7-\delta }$ : Influence of magnetic scattering

Abstract

We report measurements of the surface impedance $Z_s=R_s+i{X}_s$ of $(P{r}_x{Y}_{1-x})B{a}_{2}C{u}_3{O}_{7-\delta }$, $(x=0,0.15,0.23,0.3,0.4,0.5)$. Increasing $Pr$ concentration leads to some striking results not observed in samples doped by non-magnetic constituents. The three principal features of the $R_s(T)$ data - multiple structure in the transition, a high residual 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 magnetism and superconductivity coexist. The low $T$ behavior of $\lambda (T)$ appears to change from $T$ to $T^4$ at large $Pr$ doping, and provides evidence of the influence of magnetic pairbreaking of the $Pr$.

5 pages, 3 eps figures, Revtex, 2-column format, uses graphicx. To appear in Physica C. Postscript version also available at http://sagar.physics.neu.edu/preprints.html