Superconducting and magnetic properties of Nb/Pd

The superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers with constant Nb layer thickness dNb = 200 Åand different interlayer thicknesses 3 Å≤dPdFe≤80 Åare investigated. The thickness dependence of the magnetization and of the superconducting transition temperature shows that for small iron concentration x the Pd1-xFex layer is likely to be in the paramagnetic state for very thin films whereas ferromagnetic order is established for x≥. The parallel critical field Bc2||(T) exhibits a transition from two-dimensional (2D) behavior where the Nb films are coupled across the interlayer, towards a 2D behavior of decoupled Nb films with increasing dPdFe and/or x. This transition allows a determination of the penetration depth $\xi_{\rm F}$ of Cooper pairs into the Pd1-xFex layer as a function of x. For samples with a ferromagnetic interlayer $\xi_{\rm F}$ is found to be independent of x