Re-entrant superconductivity in the superconductor/ferromagnet V/Fe layered system

We study the superconducting properties of a series of Fe/V/Fe trilayers with variable thickness of the Fe layer and constant thickness of the V layer. For an optimized combination of thicknesses and structural quality of the thin films we observe a re-entrant behavior of the superconducting state when plotting the superconducting transition temperature T-c as a function of the Fe thickness d(Fe). With increasing d(Fe), T-c drops sharply up to d(Fe)similar or equal to8 Angstrom, then the superconductivity disappears, and it restores again at d(Fe)greater than or equal to12 Angstrom.