Magnetic Behaviour of Polycrystalline Magnetite Thin Films with Nano-Sized Crystallites

Abstract

The magnetic behaviour of ferrite solids the nanometer size mode, as their dimensions approach the atomic scale, is of increasing fundamental and applied interest in materials research. The nano-particle can be considered as a state of matter on the borderline between the atomic and crystalline states; it possesses the encoded characteristics of the material in a pure form, without the defects typical for the micro-sizes in the case of complex crystal structures, such as ferroxides. On the other hand, its dimensions are comparable to the exchange lengths of the crystal anisotropy and stray-field energy which govern the magnetic behaviour in magnetic thin films. The scientific study of these nearly “ideal” crystallites in polycrystalline thin-film ensemble is, therefore, of considerable importance. Furthermore, thin films of spinel ferrites exhibit excellent chemical stability and high corrosion resistivity and seem to be applicable as recording media and microwave absorbing layers. The nano-size and the shape of the solid may be used as design variables to tailor a material’s properties such as hysteresis losses, frequency dependence of the susceptibility and magnetooptical effects. As a result, the development of new technologies for ferrimagnetic oxide powders and polycrystalline films layered the nanometric scale is extremely important in exploring this new state of the solids.