Emission and capture of spin‐polarized electrons during ion reflection at magnetic surfaces: A new tool in surface magnetism

Abstract

Using electron‐capture spectroscopy (ECS) and electron emission spectroscopy (EES), the electron‐spin polarization (ESP) at the topmost surface layer of ferromagnetic materials is investigated. In ECS, the capture of spin‐polarized electrons during grazing‐angle surface reflection of fast deuterons is used to investigate the ESP due to long‐ranged and short‐ranged ferromagnetic order. In EES, the ion‐induced emission of low‐energy, spin‐polarized electrons from magnetic surfaces is used to study long‐ranged surface ferromagnetic order. The surfaces are well characterized using Auger electron spectroscopy, low‐energy electron diffraction, reflection high‐energy electron diffraction, and scanning tunneling microscopy. Nonzero ESP is found at surfaces of atomically clean, amorphous Fe80 B20 and (110)‐surface‐oriented Ni picture‐frame single crystals. We have studied the energy‐resolved ESP of the emitted electrons at Ni(110) surfaces. The energy distribution of the ion‐induced emitted electrons is strongly different from that of electron‐induced secondary electrons and shows a marked spin dependence. The found energy and spin distributions of the electrons, originating from the topmost surface layer, bear a close resemblance to the electronic and magnetic properties of Ni(110) surfaces. The net average ESP of the emitted electrons amounts to +5.5%, which is close to the total net Ni magnetization of +5.6%.