Magnetic circular dichroism in soft X-ray emission of itinerant and localized magnets

I present spin-resolved valence band studies of magnetic Sd-transition metal materials using magnetic circular dichroism in soft X-ray emission (SXEMCD). The non-resonantly excited SXEMCD of Fe, Co, and Ni, as well as several compounds with ferromagnetically aligned Mn atoms are compared. A simple model picture accounts for the basic principles involved. Quantitative estimates show that it is likely that substantial valence-band relaxation due to the intermediate-state core hole takes place in itinerant systems. A z+1 approximation shows that the magnitude of SXEMCD is proportional to the magnetic moment of such a core hole impurity. Magnetic circular dichroism in resonant inelastic X-ray scattering (RIXS) is discussed. For strongly localized Sd-electrons as found in some Mn compounds RIXS probes dd-excitations and the corresponding MCD. For more itinerant systems, such as iron, it is argued that RIXS leads to the observation of a convolution of the occupied and (parts on the unoccupied 3d-bands. Finally, an overview of possible future developments in helicity-resolved SXES is given. (C) 2000 Elsevier Science B.V. All rights reserved.