ION-SURFACE INTERACTION TO STUDY ION-INDUCED CAPTURE AND EMISSION OF POLARIZED ELECTRONS: NOVEL MEANS TO INVESTIGATE SURFACE MAGNETISM * C. RAU and K. WATERS

The electron spin polarization (ESP) at surfaces of bulk and thin film ferromagnetic materials has been investigated using electron capture spectroscopy (ECS), which probes the ESP of the topmost surface layer. At surfaces of PtMnSb, Tb and Fe,,B,,, we find nonhero ESP due to long-ranged or short-ranged ferromagnetic order. The sign of the ESP at surfaces of the Heusler alloy PtMnSb is in agreement with recent band structure calculations. At surfaces of the rare-earth Tb, we find that, contrary to bulk behavior, long-ranged ferromagnetic order exists far above the bulk Curie temperature (TCb = 220 K) up to a surface Curie temperature T,, = 248 K. At surfaces of the spin glass FesaB,,, we find, in agreement with ECS data, that the ESP of ion-induced emitted polarized secondary electrons is extremely sensitive to the cleanness of the topmost surface layer.