Analysis of cobalt-doped iron oxide thin films by synchrotron radiation

Surface and bulk structures of as-deposited Fe3O4 and post-oxidized γ-Fe2O3 thin films were successfully identified by synchrotron diffraction analysis. A new synchrotron diffraction method which combines the Seemann-Bohlin and the grazing incidence techniques was used to record polycrystalline diffraction patterns for structure depth profiling analysis. The post-oxidized film was found to have an α-Fe2O3 layer at the surface and γ-Fe2O3 in the bulk of the film. The formation of a thermodynamically stable antiferromagnetic α-Fe2O3 surface caused the magnetically dead layer previously detected by neutron reflection analysis. Synchrotron diffraction results also showed that the structure of the as-deposited film remains constant throughout the thickness of the film. The presence of a superlattice (300) peak indicates the film has been oxidized beyond Fe3O4. © 1987.