Influence of adsorbates and substrate interdiffusion on the spin-dependent electron scattering of Fe/Ag(001): Exploration of the parameter space for an electron spin detector

The elastic low-energy electron scattering of ferromagnetic Fe(001) films on Ag(001) exhibits a strong spin dependency, an effect that has been utilized for spin detection in electron spectroscopy. The quality of the substrate crystal, the morphology of the Fe film, and the exposure to adsorbates all have a strong influence on the spin-dependent electron scattering. These effects are especially prominent at low electron energies. Annealing of the Fe layer leads to interdiffusion. We observe that Ag migrates through the Fe film and forms a thin layer at the surface. Since the exchange asymmetry does not decrease, protection of the Fe film against residual gases by a Ag layer promises longer lifetimes for a spin detector without a significant loss of detection efficiency.