Suppression of the superconducting critical current of Nb in bilayers of Nb/SrRuO ₃

In bilayers consisting of ferromagnetic and superconducting films, the ferromagnetic film in its domain state induces inhomogeneous distribution of magnetic fields in the superconducting film. When the ferromagnetic film has bubble magnetic domains in a labyrinth structure, it has been found that the pinning of the vortices increases; hence, the critical current of the superconducting film becomes larger. Here we study the effect of parallel ferromagnetic domain structure in Nb SrRuO3 on the critical current of Nb with current flowing perpendicularly to the domains and find that in this case the ferromagnetic domain structure decreases the critical current.