FERRUM: A New Highly Efficient Spin Detector for Electron Spectroscopy

To overcome the restrictions of conventional spin detectors (Mott, SPLEED) low energy electron scattering at a Fe(100)-p(1x1) O surface was first proposed by Bertacco and Ciccacci [Phys. Rev. B 5 9, 4207 (1999)] as a system for highly efficient spin detection. We developed a new instrument based on that scheme. The iron is prepared in - situ on a W(100) crystal without the need for separate sample preparation and exchange when using a MgO substrate. Our working point at 6.5 eV scattering energy is consistent with the above paper by Bertacco and Ciccacci. Results obtained with UPS on an Fe film are shown. With a Sherman-function of approx. 30% and a reflectivity of up to 10% the figure of merit (FOM) is more than one magnitude higher compared to conventional detectors. The FOM shows no degradation over days in UHV.