Electronic and magnetic properties of thin films probed by Auger photoelectron coincidence spectroscopy (APECS) RID G-2497-2011 RID G-7348-2011 RID H-3269-2011

The recently discovered capabilities of Auger-photoelectron coincidence spectroscopy (APECS), i.e., the emission depth selectivity and the final spin state selectivity, are reviewed and discussed as a tool for the study of complex systems like magnetic thin films and multilayers. After a brief overview of these recent findings and a description of a clear experimental evidence for a dichroic effect in angle resolved (DEAR) APECS, results of coincidence Auger line shape applied to Co film on Cu(001), are presented. The geometrical configurations used, achieved by means of the high degree of freedom available in the experimental apparatus, are discussed in detail, as well as all the possible combinations that can provide a spin final state selectivity are presented. Due to the very high statistics achieved in the measurement, some finer details can be resolved at energies corresponding to transitions involving electrons from the top and the bottom of the valence band, when comparing singlet versus triplet contributions. As a first attempt and in the simplest approach, the observed dichroism can be explained by appropriate convolutions of the majority and minority densities of states, possibly corrected by a Cini-Sawatzky model for taking into account spin dependent correlation effects. (c) 2006 Elsevier B.V. All rights reserved.