Magnetic and Transport Properties of Nb/PdNi Bilayers

We investigated the superconducting proximity effect in both Nb(35 nm)/PdNi superconductor (S)-ferromagnet (F) bilayer and Nb–Nb(10 nm)/PdNi–Nb (S–SF–S) variable-thickness bridges (VTBs). In ${\rm Nb}(35\ {\rm nm})/{\rm PdNi}(d_{F}\ {\rm nm})$ SF bilayer, non-monotonic behavior of the superconducting transition temperature $T_{c}$ was observed as a function of PdNi thickness, $d_{F}$. This non-monotonic behavior of $T_{c}$ can be interpreted from the view point of damped oscillatory superconducting order parameter induced in F-layer, and the effective exchange energy $E_{ex}$ extracted from the data was approximately 150 K. On the other hand, in VTBs, it was found that the superconducting critical current $I_{c}$ was monotonically decreased with increasing $d_{F}$.