Oscillation of the superconducting critical temperature in superconductor/ferromagnet bilayers

Abstract

Present work reports the results of proximity effect investigation for superconducting Nb-Cu/Ni bilayers with the thickness of the ferromagnetic layer (CuxNi1-x) being in sub-nanometer scale. It was found a non-monotonic behavior of the critical temperature, Tc , i.e. its growth with the ferromagnetic layer thickness increasing , dF , for series of samples with constant thicknesses of Nb layer, dNb = const. The possible reasons of the Tc non-monotonic behavior at the sub-nanometer range of dF variation are discussed.