Kerr Ellipticity and Optical Response of Amorphous Rare-Earth Transition-Metal Thin Films at Shorter Wavelength

The Kerr ellipticity angle ¿k of TbFeCo film and its influence on the magnetooptic response of magnetooptic media were investigated. The ¿k was derived throughout the wavelength range from 400 to 830 nm by a simple method which adjusts the calculated value of the Kerr rotation angle to match the measured value by varying the value of ¿k. The Kerr ellipticity angle ¿k of TbFeCo film increased with shortening wavelength, although the Kerr rotation angle ¿k decreased. The contributions to the Kerr rotation angle of ¿k and ¿k for films with an enhancing structure could be separated, and were found to be additive; the latter was more dominant at shorter wave-lengths. It was also shown that the maximum value of the figure of merit of four-layer media is enhanced by the contribution of ¿k.