Superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers

The superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers with constant Nb layer thickness d(Nb) = 200 Angstrom and different interlayer thicknesses 3 Angstrom less than or equal to d(PdFe) less than or equal to 80 Angstrom are investigated. The thickness dependence of the magnetization and of time 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 greater than or equal to 0.13. The parallel critical field B-c2 parallel to (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(F) of Cooper pairs into the Pd1-xFex layer as a function of x. For samples with a ferromagnetic interlayer xi(F) is found to be independent of x.