Quantitative magnetic soft X-ray spectroscopy of buried layers in reflection mode

The combination of spectral information obtained with x-ray magnetic circular dichroism (XMCD) and X-ray resonant magnetic reflectometry (XRMR) gives the possibility to measure small magnetic moments and its arrangement especially at the interfaces. Utilizing well established XMCD based sum rules enables the element specific determination of absolute spin and orbital moments, even for a small amount of uncompensated magnetic moments in exchange bias (EB) systems. The measurement of the energy dependent reflection with constant momentum transfer (qz) gives XMCD like spectra. The advantage of this method is the simplified interference condition, because reflection is only affected by the energy dependent absorption and not by the momentum transfer. Using our advanced simulation tool ReMagX for analysis, i.e. fit of the data, it is possible to identify the magnetic spectroscopic nature for both, the rotatable and the pinned magnetic moments at the interface. As an example, we show const qz results of a widely studied EB-system, of polycrystalline iron (Fe)-manganese as an antiferromagnet and cobalt as a ferromagnet. The information for Fe obtained also in resonant reflection at the L3 edge at a very thin layer of uncompensated moment's right below the interface.