  The Fe$_3$O$_4$(111)/graphene/Ni(111) trilayer is proposed to be used as an
ideal spin-filtering sandwich where the half-metallic properties of magnetite
are used. Thin magnetite layers on graphene/Ni(111) were prepared via
successive oxidation of thin iron layer predeposited on graphene/Ni(111) and
formed system was investigated by means of low-energy electron diffraction
(LEED) and photoelectron spectroscopy (PES) of core levels as well as valence
band. The electronic structure and structural quality of the graphene film
sandwiched between two ferromagnetic layers remains unchanged upon magnetite
formation as confirmed by LEED and PES data.
