CRITICAL FIELDS IN VANADIUM-BASED SUPERCONDUCTING FERROMAGNETIC MULTILAYERS

We have made a detailed investigation of the critical fields H-c2 in s uperconducting/ferromagnetic (S/F) multilayers for the case that the F layer thickness is such that the S layers are completely decoupled. T he superconductor is vanadium; following an earlier study with Fe as f erromagnetic material, we now have varied the magnetic moment in the F layers by using Co and Ni, and by using the alloys V47Fe53 and V62Fe3 8. AU have lower moments than Fe. We show that the temperature depende nce of the critical fields can be well described by the existing theor y in all cases. Small differences in the description for Fe and the Fe based alloys on one hand and Co and Ni on the other are probably due to the increasing lattice-parameter mismatch and the resulting effect on the V properties.