Optical and Magneto-Optical Properties of Multilayer Nanosized [Co/TiO2]n Films

The optical and magneto-optical properties of the metal-dielectric multilayer [Co/TiO2](n) structures with 2-4-nm-thick layers prepared on a silicon substrate Si(001) by ion-beam deposition have been studied. The complex permittivity of multilayer [Co/TiO2](n) structures has been measured by the optical ellipsometry technique in the spectral range of 0.6-5.6 eV and analyzed using the optical reflection matrices for isotropic multilayer dielectric structures taking into account the optical losses and also using the method of anisotropic effective medium. The magneto-optical Kerr effect has been measured by the polarimetric technique in the spectral range of 1.2-4.5 eV in the polar and longitudinal geometries. The magnetic anisotropy type is determined on the base of the field dependences of the magneto-optical Kerr effect. It is found that the nanosized [Co/TiO2](n) structures can be considered as artificial optically uniaxial media with a strong magnetic and optical anisotropy at room temperature.