OPTICAL AND MAGNETOOPTICAL CONSTANTS OF PR SUBSTITUTED TBFECO FILMS

Optimization of tri- or quadrilayer magneto-optic recording media requ ires knowledge of the optical and/or magneto-optical constants for all of the individual active or passive layers that together comprise the complete disk structure. The optical (n + ik) and first-order magneto -optical (Q1 + iQ2) constants for two series (i) (Tb23Fe72.5Co4.5)100- xPrx, (ii) (Tb27Fe65Co8)100-xPrx of Pr substituted TbFeCo films, for w hich x varies between 0 and 30, have been determined by a combination of ellipsometry and Kerr polarimetry. Ellipsometry has also been used to determine independently the optical constants of the optimized SiN passivation layers developed to protect these samples. Using constants determined experimentally on thick samples, the variation of the pola r Kerr rotation and ellipticity as a function of magnetic film thickne ss has been calculated for light incident from both the air and substr ate side of a typical trilayer magneto-optic disk structure in which m aterial from the above series, the magnetic and thermomagnetic propert ies of which have been previously reported [Carey et al., J. Magn. Mag n. Mater. (to be published)], forms the active storage layer. The agre ement obtained with measurements demonstrates the self-consistency of the modeling process and the validity of the determined constants.