Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Surface or interface magnetism
O 28.1: Vortrag
Dienstag, 23. März 2010, 10:30–10:45, H48
Electron pair emission from ferromagnetic surfaces — •Frank O. Schumann1, Carsten Winkler1, Jürgen Kirschner1, Franz Giebels2, Herbert Gollisch2, and Roland Feder2 — 1Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle, Germany — 2Theoretische Festkörperphysik,Universität Duisburg-Essen, 47048 Duisburg, Germany
We present a combined experimental and theoretical study of the electron pair emission from a Fe(001) surface which is excited by a spin-polarized primary electron beam. The aim is to study the spin dependence of the exchange-correlation hole. The in-plane magnetization direction of the Fe sample can be controlled by an external magnetic field. A spin-polarized primary beam hits the Fe(001) surface along the surface normal and the spin polarization of the beam is either parallel or antiparallel to the magnetization direction. The emitted electron pairs are detected via a time-of-flight coincidence set-up. The data are grouped into two subsets for which the spin polarization of the majority electrons is either parallel or antiparallel to the primary beam. We find that the angular distributions of the coincidence intensity are spin dependent. Furthermore, we are able to identify favorable conditions, which ensure that the scattering partner of the primary electron has a high spin polarization. This allows us to separate the contribution of the exchange from the Coulomb correlation to the size of the exchange-correlation hole. We find that the exchange part has a larger extension than the Coulomb part confirming a suggestion by Slater more than 75 years ago.