Magneto-optical polarization spectroscopy with soft X-rays

Abstract

X-ray magneto-optical polarization spectroscopy is a relatively new ellipsometric technique with which the complete polarization state of X-ray radiation after its interaction with magnetic matter can be measured. This comprises rotation and ellipticity, which fully quantify the light’s polarization. Employing this technique, the complete magneto-optical constants in the X-ray regime can directly be obtained, in contrast to the more commonly used intensity-only measurements. The Faraday and magneto-optical Kerr effects, being odd with respect to magnetization reversal, can be used for the examination of ferromagnetic (FM) materials. This we demonstrate here with Faraday and Kerr rotation and ellipticity spectra, measured at the 2p edges of Fe, Co, and Ni. The Voigt effect and magnetic linear dichroism (XMLD), which are even with respect to magnetization reversal, are applied to probe both FM and antiferromagnetic (AFM) materials. Using a new XMLD-reflection spectroscopy we present results obtained on technologically important buried AFM NiO layers.