In Situ Observations of Magneto-Optical Spectra for Polycrystalline Co Films in Early Stage of Deposition

In situ measurements of the longitudinal Kerr effect were used in conjunction with ellipsometry measurements over the photon energy range from 2.0 to 4.6 eV to investigate the magneto-optic properties of polycrystalline Co films deposited on fused quartz substrates. AFM observations and ellipsometry measurements show that Co forms islands on the substrate in the early stages of deposition, and that the films become continuous in an optical sense when their thickness is about 60Å. The spectral shapes of both the real and imaginary parts of ¿¿xy show significant changes for 100Å thick films and for films less than 60Å thick. The dependence of the spectral shape on the Co coverage is discussed in relation to the film structure. Below 30Å, the calculated ¿¿xy based on formulae for the effective dielectric tensor of a composite material containing fine magnetic particles, and using the measured permittivity of a 100Å thick Co film, agrees well with the experimental results.