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

Abstract

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 $d_{\mathrm{Fe}}\simeq 8\hspace{0.5em}\mathrm{\AA },$ then the superconductivity disappears, and it restores again at $d_{\mathrm{Fe}}>~12\hspace{0.5em}\mathrm{\AA }.$