Superconducting spin valve effect in Fe/Si3N4/Pb/Si3N4/Fe heterostructures

The structures of the superconducting spin valve (SSV) ${\mathrm{Fe}/\mathrm{Si}}_{3}{\mathrm{N}}_{4}/\mathrm{Pb}/{\mathrm{Si}}_{3}{\mathrm{N}}_{4}/\mathrm{Fe}$ (where ${\mathrm{Si}}_{3}{\mathrm{N}}_{4}$ is a dielectric insulating layer of controlled thickness) were investigated. The dependence of the magnitude of the SSV effect on the thicknesses of the superconducting (S) and insulating (I) layers was studied. Optimization of the S and I layer thicknesses enabled a complete switching between the normal and superconducting states when the mutual orientation of the magnetizations of the ferromagnetic (F) layers changed from antiparallel to parallel. A maximal SSV effect value of 0.36 K was achieved in an external magnetic field of 1 kOe. These results demonstrate that SSV structures with tunable S/F interface transparency controlled by insulating interlayers are promising for achieving a significant magnitude of the effect. This opens new avenues for the development of such systems and their potential applications in spintronic devices.