  The magnetic behavior of thin ferromagnetic itinerant-electron films is
investigated within the strongly correlated single-band Hubbard model. For its
approximate solution we apply a generalization of the modified alloy analogy
(MAA) to deal with the modifications due to the reduced translational symmetry.
The theory is based on exact results in the limit of strong Coulomb interaction
which are important for a reliable description of ferromagnetism. Within the
MAA the actual type of the alloy analogy is determined selfconsistently. The
MAA allows, in particular, the investigation of quasiparticle lifetime effects
in the paramagnetic as well as the ferromagnetic phase. For thin fcc(100) and
fcc(111) films the layer magnetizations are discussed as a function of
temperature as well as film thickness. The magnetization at the surface-layer
is found to be reduced compared to the inner layers. This reduction is stronger
in fcc(100) than in fcc(111) films. The magnetic behavior can be
microscopically understood by means of the layer-dependent spectral density and
the quasiparticle density of states. The quasiparticle lifetime that
corresponds to the width of the quasiparticle peaks in the spectral density is
found to be strongly spin- and temperature-dependent.
