Spinel ferrites (XFe2O4 where X is a divalent transition metal cation), comprise an oxide family with a large range of electronic and magnetic properties relevant for high-temperature spintronic applications. Magnetite (Fe3O4) is one of the attractive materials as it is predicted to be half-metallic at room temperature but also multiferroic at lower temperature. The search for new materials with the capability of generation of significant spin-polarized currents at room temperature has sparked renewed interest in Fe3O4 but also in CoFe2O4, NiFe2O4 and MnFe2O4, whose insulating behaviour and high Curie temperatures make them exciting candidates for spin filtering. In our laboratory, we have developed an oxygen plasma-assisted molecular beam epitaxy technique specially dedicated to the epitaxial growth of ferrite layers [1]. By mastering the crystalline growth of Fe3O4, CoFe2O4, NiFe2O4 or MnFe2O4 thin films and associated heterostructures (spin valves, tunnel junctions), promising effects were observed such as magnetic exchange coupling at the spinel/spinel interface, magnetoresistance effects (GMR, TMR) or spin filtering across magnetic tunnel barriers [2,3]