Fully relativistic description of the magneto-optical properties of arbitrary layered systems

A fully relativistic formalism is presented that allows us to define the frequency-dependent optical conductivity tensor for arbitrary layered systems in a layer-resolved way. This opens in particular the way to deal with the magneto-optical properties of magnetic surface layer systems and to calculate the corresponding magneto-optical Kerr spectra. The formalism, based on a fully relativistic description of response theory in arbitrary order, is described in some detail. For an implementation the very flexible spin polarized relativistic Korringa-Kohn-Rostoker method of band structure calculation has been used. Results of corresponding applications to the elemental ferromagnets bcc-Fe and fcc-Co treated as homogeneous layer systems are presented.