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

摘要

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° and 60°. 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.