Interfacial mixing of ultrathin Cr films on Fe(100) studied by Auger electron spectroscopy

Abstract

The chemical composition of ultrathin Cr films grown on Fe(100) under layer-by-layer conditions has been studied by proton- and electron-induced Auger electron spectroscopy. Exploiting the largely different probing depths for proton and electron excitation we can quantitatively evaluate the layer-dependent concentration profiles of Cr and Fe in the film. The main results are: (1) for a coverage of 1 ML about half of the deposited Cr atoms exchange places with Fe atoms; (2) place exchange processes are essentially confined to the topmost and second layer; (3) for coverages larger than 3 ML the topmost layer consists almost exclusively of Cr atoms; (4) the as-grown 1 ML films are not stable.