Specular reflection of spin-polarized electrons from the W(001) spin-filter crystal in a large range of scattering energies and angles

Abstract

Extending previous work on the imaging spin-filter technique based on electron diffraction from W(001) in the specular (00)-LEED (low-energy electron diffraction) spot, we studied the scattering-energy and angle-of-incidence landscape of spin sensitivity $S$ and reflectivity ${I/I}_{0}$. The setup includes a spin-polarized GaAs electron source and a rotatable delay-line detector for spatially resolving detection. We measured the intensity and spin asymmetry of the specularly reflected beam for energies between 14 and 37 eV and angles of incidence between ${30}^{\ensuremath{\circ}}$ and ${60}^{\ensuremath{\circ}}$. Resulting energy-angular landscapes show rather good agreement with theory [relativistic layer KKR SPLEED (spin-polarized low-energy electron diffraction) code]. This provides a sensitive test of theory, in particular of details of the surface barrier. The results identify several regions of high asymmetry and figure of merit, in particular a region where the asymmetry can be ``switched'' between positive and negative values by just 4 eV energy variation.