Magnetic circular dichroism and resonant X-ray scattering at the L_2_,_3 absorption edges of 3d-transition metals in magnetic layer-systems

Magnetic Circular Dichroism (MCD) at the L2,3 absorption edges of 3d transition elements is studied with circularly polarized synchrotron radiation. The validity of sum rules, with which one can determine element specifically the spin- and orbital magnetic moments from the polarization dependent absorption spectra, is tested for the ferromagnets Fe, Co and Ni. We have investigated the differences in MCD of Fe, Co and Ni L2,3 absorption edges measured with electron yield (EY) and fluorescence yield (FY) detection of the absorption signal. The experimentally determined spectra are compared to first-principle calculations. The magnetic coupling of Cr to Fe inside a Fe/Cr multilayer with one atomic layer of Cr between adjacent ferromagnetically coupled Fe films is shown to be antiparallel with a magnetic moment of Cr of about -0.3 #mu#_B The dichroism signal of two atomic Cr layers in the same systems nearly vanishes, obviously due to magnetic frustration in the Cr film. In the fluorescence yield detection mode, resonant X-ray scattering effects are observed at Fe/Cr and Co/Mn multilayer systems and single Fe films depending on their structure (especially their thickness) and on the measurement geometry. These effects express themselves in additional intensity at the L2,3 white lines, and the dichroism asymmetry can be enhanced drastically. X-ray reflection measurements on these systems have shown, that the dichroism signal can be strongly enhanced at the absorption edges in reflection. Apart from the absorption edges, additional structures are also found in the energy dependent reflection-spectrum, which are related to multilayer reflection peaks. This is verified by reflection calculations on these systems. (orig.)SIGLEAvailable from TIB Hannover: RA 831(2994) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman