Soft X-ray resonant Kerr effect as a depth-sensitive probe of heteromagnetic nanostructures

We report on a significantly improved depth sensitivity of soft x-ray resonant magneto-optical Kerr effects that is useful to resolve depth-varying magnetic properties in complex multilayered structures. Using model systems having depth-varying spin structures in a magnetic ultrathin layer, we calculate the Kerr rotation and ellipticity as a function of the grazing angle of incident s-polarized soft x-rays and their magnetization hysteresis loops as well. It is found that the depth sensitivity is considerably changed with the grazing angle as well as the photon energy near the element-specific resonance regions. This extremely large sensitivity can be interpreted based on the complex Kerr vector sums of individual contributions from each depth within a single magnetic layer.