  In this work we analyse the role of a thin Cr spacer between Fe and Gd layers
on structure and magnetic properties of a [Fe(35A)/Cr(tCr)/Gd(50A)/Cr(tCr)]x12
superlattice. Samples without the Cr spacer (tCr=0) and with a thin tCr=4A are
investigated using X-ray diffraction, polarized neutron and resonance X-ray
magnetic reflectometry, SQUID magnetometery, magneto-optical Kerr effect and
ferromagnetic resonance techniques. Magnetic properties are studied
experimentally in a wide temperature range 4-300K and analysed theoretically
using numerical simulation on the basis of the mean-field model. We show that a
reasonable agreement with the experimental data can be obtained considering
temperature dependence of the effective field parameter in gadolinium layers.
The analysis of the experimental data shows that besides a strong reduction of
the antiferromagnetic coupling between Fe and Gd, the introduction of Cr
spacers into Fe/Gd superlattice leads to modification of both structural and
magnetic characteristics of the ferromagnetic layers.
