Magnetic penetration depth of Y1-xPrxBa2Cu3O6.97 measured by muon-spin relaxation

We have measured the magnetic penetration depth of the high-Tc superconducting system Y1-xPrxBa2Cu3O6.97 for 0.05≤x≤0.4 using the technique of transverse-field muon-spin relaxation. The temperature dependence is similar to that of the related compounds YBa2Cu3O7-δ with varying oxygen content. The zero-temperature relaxation rate and Tc both decrease monotonically with x, in a manner similar to those of YBa2Cu3O7-δ with increasing δ. This observation is consistent with the interpretation that Pr is nearly tetravalent in this system so that Tc is largely suppressed by means of the filling of holes in the conducting CuO2 planes. The influence of pair breaking, finite mean free path, and correlation with results for other high-Tc superconductors are discussed.