Resonant magneto-optical properties of Fe near its2plevels: Measurement and applications

Resonant magneto-optical properties of Fe are considered across its $2p$ core levels. General equivalence of the classical magneto-optical formalism (dielectric tensor) and the resonant atomic scattering factor in the electric dipole approximation is shown in describing pure charge contributions as well as first- and second-order magnetic contributions. Thickness effects in transmission absorption measurements are considered and shown to be minimized in Faraday magneto-optical rotation measurements. Transmission absorption and Faraday rotation spectra obtained using linear polarization are normalized to the complex refractive index and atomic scattering factor for pure circular modes and their polarization average, showing that the pure magnetic part is roughly 50% of the pure charge part at the $L_3$ resonance. Magnetic linear dichroism (Voigt effect) measured in transmission is only 2% of the pure charge scattering at resonance. These magneto-optical constants are used to calculate important polarization-dependent experimental quantities including penetration depths, critical angles for total external reflection, Kerr rotation and intensity spectra, and interference and distorted-wave effects that modulate scattering intensities. The results reveal the importance of knowledge of these properties and use of full magneto-optical formalisms in planning and interpreting experiments involving resonant $2p$ optical properties of the $3d$ transition metals.