Magnetorefractive effect in magnetic nanocomposites

The magnetorefractive effect in ferromagnetic metal-insulator granular nanostructures (CoFeZr)-SiOn, Co-Al-O, FeSiOn, and (CoFe)-(Mg-F) is investigated in the infrared spectral region in a wavelength range from 5 to 20 mum. The magnitude of the effect varies from 0.1 to 1.5% for different nanocomposites and strongly depends on the frequency of light and magnetoresistance. It is shown that the reflection coefficient changes in a magnetic field not only due to the magnetorefractive effect, but also due to the even magnetooptical effect. Simple relations describing this effect are given for the case when the reflection from the substrate is insignificant and in the case of a three-layer (insulator-film-substrate) system. The expression for the frequency dependence of the magnetorefractive effect in nanocomposites is derived and its features in the case of high-frequency spin-dependent tunneling are analyzed. (C) 2003 MAIK "Nauka/Interperiodica".