Magnetic circular versus linear dichroism effects: A case study at the Fe M2,3 edge (abstract)

Abstract

Magneto-optical measurements are strongly dependent on the polarization of the radiation as well as the interaction geometry of the light with respect to the relative orientation and direction of the magnetization M. In an effort to identify the different angular and spectral contributions and to select the preferred experimental setup for magneto-optical measurements, we performed magnetic circular dichroism (MCD) and magnetic linear dichroism (MLD) measurements around the Fe M2,3 transition. The MCD experiments were performed by measuring the difference between the reflected intensities of left and right circularly polarized soft x-ray radiation. While for the MCD experiments, the magnetization was kept constant, it was modulated between M+ and M− for the MLD spectra. We used a quadruple reflection polarizer that was tuned to act as a λ/4 phase shifter for the MCD measurements and as a linear polarizer for the MLD experiments. The experiments confirm our model calculations for longitudinal and polar MCD and transverse MLD using a previous determined energy-dependent dielectric tensor ε(ω). The outcome of our experiments has consequences for most MCD experiments performed with Pcirc<1 in combination with mixed geometry. Such a configuration could severely alter the quantitative MCD analysis due to the strong MLD contribution.