Auger electron spectroscopy analysis of interface roughness of Fe/Cr bilayers

In this work we investigate the surface and interfacial properties of Fe/Cr and Cr/Fe bilayers before and after annealing using Auger electron spectroscopy (AES). The roughness of the interface is also determined with the X-ray reflection method. The fitted values of inelastic mean free path λ_{Cr in Fe} reproduce the calculated value for Cr in Fe well, whereas the values of λ_{Fe in Cr} are significantly larger than the calculated ones, suggesting mutual segregation of atoms during growth. The low-energy range Auger spectra demonstrated that the MNN lines of Cr covered with Fe and Fe covered with Cr disappear after the deposition of 1 nm overlayer, this being an indication of continuous deposited film, but not excluding mixing at interfaces. The results of X-ray reflectometry measurements, which give the values of Fe/Cr and Cr/Fe roughness, are in accordance with this observation. The LMM Auger spectra of annealed samples showed that at the largest applied temperature, Cr diffuses into Fe, but the reverse effect of Fe diffusion into Cr is not observed.