Secondary emission from W(1Â 1Â 0) excited by spin-polarized electrons

Energy distribution curves (EDC) of secondary electrons from W(1 1 0) were measured for spin-up (I+) and spin-down (I−) polarization of the incident beam. The intensity asymmetry, defined as A = (I+ − I−)/(I+ + I−), for a certain experimental geometry was measured as large as 7%. This asymmetry was explained in terms of a “spin-filter” effect. The model assumes that the secondary electrons excited by spin-polarized primary electrons are spin-polarized inside the solid. On the way to the vacuum they undergo spin-orbit interaction on the surface barrier that provides the spin-dependent and energy selective transmission through the surface.