Origin of the Inverse Spin Switch Effect in Superconducting Spin Valves

Known as the spin switch effect (SSE), the resistance of a ferromagnet/superconductor/ferromagnet (F/S/F) spin valve near its superconducting transition temperature T(c) is different for parallel (R(P)) and antiparallel (R(AP)) configurations of the F layers. Here, we report the observation of the coexistence of the standard (R(P)> R(AP)) and inverse (R(P)< R(AP)) SSE in Ni(81)Fe(19)/Nb/Ni(81)Fe(19)/Ir(25)Mn(75) spin valves. Our measurements reveal that the inverse SSE arises from a dissipative flow of vortices induced by stray magnetic fields from Neacuteel domain-wall pairs in the F layers.