  On the basis of phenomenological Ginzburg-Landau approach we investigate the
problem of order parameter nucleation in hybrid superconductor/ferromagnetic
systems with a domain structure in applied external magnetic field. Both the
isolated domain boundaries and periodic domain structures in ferromagnetic
layers are considered. We study the interplay between the superconductivity
localized at the domain walls and far from the walls and show that such
interplay determines a peculiar field dependence of the critical temperature
Tc. For a periodic domain structure the behavior of the upper critical field of
superconductivity nucleation near Tc is strongly influenced by the overlapping
of the superconducting nuclei localized over different domains.
