Optical and magnetooptical properties of CoFeB/SiO2 and CoFeZr/Al2O3 granular magnetic nanostructures

摘要

The optical and magnetooptical properties of the new granular nanocomposites (CoFeB)/(SiO2) and (CoFeZr)/(Al2O3), which are grains of amorphous ferromagnetic alloys embedded in dielectric matrices, have been studied. The dependence of the optical, magnetooptical, and magnetic properties of the nanocomposites on their qualitative and quantitative composition, as well as on the conditions of their preparation, was investigated. Spectra of the dielectric functions epsilon = epsilon(1) - iepsilon(2) were obtained by the ellipsometric method in the range 0.6-5.4 eV. Above 4.2 eV, the absorption coefficient of the (CoFeB)/(SiO2) composites was found to be close to zero for all magnetic-grain concentrations. The polar Kerr effect measured at a photon energy of 1.96 eV in dc magnetic fields of up to 15 kOe reaches values as high as 0.25degrees-0.3degrees for these nanocomposites and depends only weakly on the conditions of preparation. On the other hand, the (CoFeZr)/(Al2O3) nanostructures reveal a considerable difference in the concentration dependences of the Kerr effect between samples prepared in a dc magnetic field and in zero field. (C) 2004 MAIK "Nauka/Interperiodica".