  We study the proximity effect in hybrid structures consisting of
superconductor and ferromagnetic insulator separated by a normal diffusive
metal (S/N/FI structures). These stuctures were proposed to realize the
absolute spin-valve effect. We pay special attention to the gaps in the density
of states of the normal part. We show that the effect of the ferromagnet is
twofold: It not only shifts the density of states but also provides suppression
of the gap. The mechanism of this suppression is remarkably similar to that due
to magnetic impurities. Our results are obtained from the solution of
one-dimensional Usadel equation supplemented with boundary conditions for
matrix current at both interfaces.
