Optical and magneto-optical constants of Pr substituted TbFeCo films

Abstract

Optimization of tri- or quadrilayer magneto-optic recording media requires 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 which 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 polar Kerr rotation and ellipticity as a function of magnetic film thickness has been calculated for light incident from both the air and substrate side of a typical trilayer magneto-optic disk structure in which material from the above series, the magnetic and thermomagnetic properties of which have been previously reported [Carey et al., J. Magn. Magn. Mater. (to be published)], forms the active storage layer. The agreement obtained with measurements demonstrates the self-consistency of the modeling process and the validity of the determined constants.