We report on large magnetic moments of up to 18.9μB∕Co in Co-doped ZnO films grown by pulse-injection metal organic chemical vapor deposition. The magnetic moment saturates easily in perpendicular magnetic fields and is considerably reduced when the magnetic field is applied parallel to the film plane. The saturation moment is largest for a small Co doping concentration of 1% and persists up to a temperature well above 900K. These extraordinary magnetic attributes cannot be explained by the spin-only moment of Co2+ ions or Co cluster, but suggest the formation of orbital states in a defect-related impurity band.

We report on large external magnetic field effects during pulsed injection metal-organic chemical vapor deposition of magnetite films on MgO͑001͒. The application of a 1 T field during the growth process significantly increases the saturation magnetization of magnetite by 150%-220% at a deposition temperature of 550 and 600°C, while the enhancement of the remanent magnetization is even larger. This anomalous magnetic field effect does not drastically alter the crystalline texture, surface morphology, and film thickness of magnetite, but is explained by a suppression of antiphase-boundary formation during film growth.

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This report is on the growth of Fe3O4 nanofilms on Al2O3(0001) and MgO(001) substrates with and without the presence of an external magnetic field using a pulsed injection metallorganic chemical vapour deposition (PI MOCVD) technique. The effects of growing magnetic oxide nanofilms in a 1 T field have been examined using various instrumental methods. It was found that the application of a magnetic field during PI MOCVD does not drastically alter the crystalline texture, surface morphology, and film thickness, but it significantly modifies the Fe3O4 film magnetisation and coercive field. Moreover, it was shown that the application of a 1 T field during the cooling of the sample also improves the magnetic properties. We believe that the large external field orients the magnetic spin structure at high temperatures (during growth or the initial stages of cool down) and that cooling through local magnetic ordering temperatures at Fe3O4 defect sites subsequently favours a ferromagnetic spin alignment. The control of magnetic properties of magnetite nanofilms by the application of magnetic fields during growth opens up new routes towards the fabrication and application of magnetic thin film devices.

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