The proximity effect in an Fe-Cr-V-Cr-Fe system

The proximity effect was studied in a thin-film Fe-Cr-V-Cr-Fe layered system. As the chromium layer thickness (d _Cr) increases at a fixed thickness of iron layers (d _Fe), the dependence of the superconducting transition temperature (T _c) on d _Cr exhibits a maximum at d _Cr ≃ 40 Å followed by a sharp decrease. Investigation of the dependence of T _c on d _Fe at a fixed d _Cr showed that the depth of penetration of the Cooper pairs into a chromium layer does not exceed 40 Å. Analysis of the results obtained suggests that, at d _Cr ≃ 40 Å, chromium layers exhibit the transition from a nonmagnetic state to an incommensurate spin density wave state.