Determination of the energy dependence of the off-diagonal terms of the dielectric tensor by means of M2,3 reflection MCD measurements (abstract)

Abstract

We present the first magnetic circular dichroism (MCD) measurements around the M edges of 3d metals utilizing SRCs recently developed quadruple reflection polarizer system. The reflection polarizer converts linearly polarized light by means of the phase shift between s- and p-reflections into either left or right circular polarized radiation. The concept of the phase shifter has been tested at a bending magnet beam line at the Aladdin storage ring using the M2,3 absorptions of magnetically ordered thin films of Fe, Co and Ni. The normalized MCD signal e.g., (IR−IL)/0.5*(IR+IL) is on the order of several % from peak to peak and scales linearly with the magnetic moments. The shape of the reflection MCD signals has a very pronounced angular dependence with a maximum around a reflection angle of θ=60°–65°. The main trends in the angular dependence of the reflection MCD signal can be verified by model calculations. The model also allows us to extract the energy dependence of the off-diagonal terms in the dielectric tensor from the experimental data. The potential use and high sensitivity to variations in the local magnetic environment will be demonstrated with high resolution measurements of several ferrimagnetic compounds.