The proximity effect in a ferromagnetic metal/superconductor nanostructure on a low magnetic field

The influence of a low magnetic field on the proximity effect in a ferromagnetic metal/superconductor (FM/S) bilayer is considered. The critical superconducting temperature $T_c(d_f,H_0)$ of the FM/S-contact is calculated as a function of FM-layer thickness $d_f$. Both in cases with and without the magnetic field $H_0$, the function $T_c(d_f,H_0)$ is shown to have qualitatively different character for various parameters of the FM/S-contact: attainment on plateau, damped oscillations, reentrant superconductivity, periodically-reentrant superconductivity. The magnetic field decreases $T_c$ and changes a reentrant superconductivity limits.