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 (RP>RAP) and inverse (RP<RAP) SSE in Ni81Fe19/Nb/Ni81Fe19/Ir25Mn75 spin valves. Our measurements reveal that the inverse SSE arises from a dissipative flow of vortices induced by stray magnetic fields from Néel domain-wall pairs in the F layers.