The effect of thermo-chemical treatment on the ease of saturation in a magnetic field of epitaxial magnetite ͑100͒ thin films grown on MgO ͑100͒ substrates was investigated. It was found that the films maintained a fully strained state with the MgO substrate during the treatment in air. No other iron oxide phase apart from the magnetite was observed in the treated film. Yet, remarkably the treated films showed a higher magnetization compared to that of original ones. A model involving a change in antiferromagnetic coupling at the antiphase boundaries during the treatment is proposed.

Surface magnetic structure of epitaxial magnetite thin films grown on MgO (001) A long-range ordered magnetic domain structure was found in magnetitelike ͑Fe 3−␦ O 4 , ␦ Ϸ 0.03͒ thin films prepared by molecular beam epitaxy on MgO ͑100͒ substrates. The stripelike magnetic domain structure arising after suitable postprocessing differs significantly from earlier observations. The field-dependent domain structure was investigated by magnetic force microscopy in external magnetic fields. The magnetic domain structure results from a moderate perpendicular anisotropy. The domain structure is pinned, and the pinning centers arise from the magnetite antiphase domain structure.

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