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 ${d}_{\mathrm{Fe}}.$ With increasing ${d}_{\mathrm{Fe}},$ ${T}_{c}$ drops sharply up to ${d}_{\mathrm{Fe}}\ensuremath{\simeq}8 \mathrm{\AA{}},$ then the superconductivity disappears, and it restores again at ${d}_{\mathrm{Fe}}>~12 \mathrm{\AA{}}.$