Superconducting and magnetic properties of Nb/Pd 1-xFex/Nb triple layers

Abstract:The superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers with constant Nb layer thickness dNb=200 Å and different interlayer thicknesses 3 Å≤ dPdFe ≤ Å are 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 ≥ 0.13. The parallel critical field $${B_{c2||}}(T)$$ 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 dPdFeand/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.