Resistive transitions under applied fields in oriented thin films of Y0.6Pr0.4Ba2Cu3O7: Evidence for conventional three-dimensional behavior

We report a detailed study of the resistive transitions in oriented films of Y0.6Pr0.4Ba2Cu3O7 (PYBCO) under applied fields. Our analysis shows a more conventional three-dimensional behavior, with no giant flux-creep effects, and a considerable increase in the coherence length as compared to that of Y1Ba2Cu3O7 (YBCO), both in the in-plane and out-of-plane directions. This large increase cannot be explained by just the magnetic pair breaking supposedly responsible for the decrease in the critical temperature. It is proposed that the extended 4f wave functions of the Pr atoms lead to a strong coupling between CuO plane, thus removing the van Hove singularity responsible for the anomalously short coherence length in YBCO.