Fine structure analysis of near-edge electron energy loss spectra related to the compositional variation at the diffuse interfaces in FeGe multilayers

Abstract

Analysis of the Fe L23 edge fine structures in electron energy loss spectra is performed with nanometer-scale spatial resolution across the diffuse interfaces in FeGe multilayers, in which an interphase (with Ge penetration into Fe layers) has been found to be nonmagnetic. Results are correlated to the chemical composition of Ge and Fe, which is obtained simultaneously by mapping the relative weight of the Fe and Ge L23 signals, in order to investigate significant differences in the Fe L23 edge fine structures of magnetized iron and of demagnetized iron due to Ge penetration. As a function of position across the multilayer we find that the L3 peak width and the relative energy interval between the L2 and L3 white lines fluctuate in concert with the Ge concentration. Furthermore, if the total weight of the white lines does not seem to change significantly, we identify an increase in the white line ratio at the interface between Ge and Fe. These results are connected to the detailed changes, at the nanometer level, of electron properties such as d-band occupation and spin pairing.