Penning de-excitation of spin-polarised metastable He atoms on magnetic surfaces: Mg on Fe

Surface magnetic properties of iron films upon Mg deposition have been investigated by means of spin-polarised metastable de-excitation spectroscopy (SPMDS). Deposition of 1 ML of Mg on iron films preserves the magnetic character of the topmost layer but modifies the metastable de-excitation mechanism. The reduction of the surface work function induced by Mg condensation changes the de-excitation mechanism from the one usually observed on 3d metal surfaces (resonant ionisation followed by Auger neutralisation) to Auger de-excitation. The effects induced on SPMDS spectra by the modification of the de-excitation mechanism are discussed.