Resonant X-ray reflectivity study of Fe/Cr superlattices

We have measured the composition profile on an Fe/Cr superlattice using glancing incidence X-ray reflectivity. Resonant reflectivity measurements were carried out by tuning the X-ray energy around the respective K-edge of Fe and Cr. We were able to obtain excellent fits to the data and get consistent geometry and composition parameters from the reflectivity measurements at six different X-ray energies. We obtained valuable information on the interface composition of the superlattice and observed also a slight variation in composition at the bottom and top interfaces. The information obtained using this method allows a determination of not only the electron density but also the composition profiles of the multilayers. This non-destructive technique is a promising tool for the determination of the chemical composition of thin film.