  We report on the magnetic and structural properties of
ferromagnetic-insulating La$_2$CoMnO$_6$ thin films grown on top of (001) STO
substrates by means of RF sputtering technique. Careful structural analysis, by
using synchrotron X-ray diffraction, allows identifying two different
crystallographic orientations that are closely related to oxygen stoichiometry
and to the features (coercive fields and remanence) of the hysteresis loops.
Both Curie temperature and magnetic hysteresis turn out to be dependent on the
oxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen
content of the films, therefore controlling their microstructure and magnetic
properties.
