The magnetic anisotropy in antiferromagnetic 500 A thick NiO films, before and after the establishment of an exchange bias field with Co84Fe16 ferromagnetic layers, was measured using magnetic linear dichroism in soft x-ray absorption. Both <111> textured NiO and untextured NiO films show exchange-bias induced in-plane magnetic anisotropy of nearly equal magnitude and with the Ni moment axis being nearly parallel to the exchange bias field direction. These results represent the first observation of the key step in the exchange biasing process, namely, repopulation of the antiferromagnetic domains whose magnetization axis is closest to the exchange bias field direction.

We have grown epitaxial Fe-doped TiO2 rutile films on rutile TiO2(110) substrates, and have explored the resulting compositional, structural, morphological and magnetic properties. Clusters of mixed TiO2 rutile and Fe3O4 form on the surface of a continuous rutile epitaxial film during growth. Room-temperature ferromagnetism is observed, and is associated with the formation of secondary phase Fe3O4 rather than a true diluted magnetic oxide semiconductor.

Ferromagnetic Co-doped rutile TiO2 single crystals were synthesized by high-temperature ion implantation and characterized by a variety of techniques. Co is uniformly distributed to a depth of ∼300 nm with an average concentration of ∼2 at. %, except in the near-surface region, where the concentration is ∼3 at. %. Ferromagnetic behavior is exhibited at room temperature with an effective saturation magnetization of ∼0.6 μB/Co atom. The Co is in a formal oxidation state of +2 throughout the implanted region, and no Co(O) is detected.

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