  SrFe$_{12}$O$_{19}$ (SFO) films grown on Si (100) substrates by
radio-frequency magnetron sputtering have been characterized in terms of
composition, structural and magnetic properties by a combination of microscopy,
diffraction and spectroscopy techniques. M\"ossbauer spectroscopy was used to
determine the orientation of the films magnetization, which was found to be
controlled by both the sputtering power and the thickness of the films.
Additionally, the coupling between the SFO films and a deposited cobalt
overlayer was studied by means of synchrotron-based spectromicroscopy
techniques. A structural coupling at the SFO/Co interface is suggested to
account for the expetimental observations. Micromagnetic simulations were
performed in order to reproduce the experimental behaviour of the system.
