Flat epitaxial ferromagnetic CoFe2O4 films on buffered Si(001)

Ferromagnetic films of spinel CoFe2O4 have been grown epitaxially on Si(001) using CeO2/YSZ double buffer layers. The heterostructures were built in a single process by pulsed laser deposition with real-time control by reflection high-energy electron diffraction. YSZ and CeO2 grow cube-on-cube on Si(001) and CoFe2O4 grows with (111) out-of-plane orientation, presenting four in-plane crystal domains. The interface with the buffer layers is smooth and the CoFe2O4 surface is atomically flat, with roughness below 0.3 nm. The films are ferromagnetic with saturation magnetization around 300 emu/cm3. The properties signal that CoFe2O4 is a good candidate for monolithic devices based on ferromagnetic insulating spinels.