  Static and dynamic magnetic properties of a ferrimagnetic
[Fe(35A)/Gd(50A)]x12 superlattice were investigated in a wide 4-300 K
temperature range using magneto-optical Kerr effect (MOKE) and ferromagnetic
resonance (FMR) techniques. The multilayer structure was sputtered on a
transparent glass substrate which made it possible to perform MOKE measurements
on both Fe and Gd terminated sides of the superlattice. These experiments
allowed us to detect a transition between field-aligned and canted magnetic
states on both sides of the film and to distinguish between the bulk and
surface twisted phases of the superlattice. As a result, the experimental H-T
magnetic phase diagram of the system was obtained. FMR studies at frequencies
7-36 GHz demonstrated a complex evolution of absorption spectra as temperature
decreased from room down to 4 K. Two spectral branches were detected in the
sample. Theoretical simulations show that the observed spectral branches
correspond to different types of inhomogeneous resonance modes in the
multilayer with non-uniform magnetization precession inside Gd layers.
