  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.
