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

Abstract

The Kerr ellipticity angle γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> of TbFeCo film and its influence on the magnetooptic response of magnetooptic media were investigated. The γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> 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 γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> . The Kerr ellipticity angle γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> of TbFeCo film increased with shortening wavelength, although the Kerr rotation angle θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> decreased. The contributions to the Kerr rotation angle of θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> and θ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> 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 γ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</sub> .