Spin-polarised metastable atom de-excitation at alkali-covered magnetic surfaces: Na on Fe/Ag(0Â 0Â 1)

Sodium adsorption on Fe/Ag(0 0 1) has been investigated by means of spin-polarised metastable de-excitation spectroscopy (SPMDS). Upon Na deposition, a strong difference in the high-kinetic-energy region of the energy distribution curves collected for the two opposite spin polarisations of the metastable atom has been observed. Above monolayer coverage, the difference changes sign indicating profound modifications of the surface magnetic properties. At higher Na coverage, a difference in the maximum kinetic energy of emitted electrons for the two polarisation directions of the metastable atom has been detected.