Large spin asymmetry in electron absorption and reflection from oxidized single crystal Fe/MgO(001) films

High quality single crystal Fe films to be used in spin polarized electron spectroscopy have been prepared in ultra-high vacuum by epitaxial growth on MgO(001) substrates. Oxygen absorption on the clean surface followed by an nealing at 600 degrees C produces a well-ordered p(1 x 1) overlayer. The lo w energy electron absorption and reflection from the Fe(001)-p(1 x 1)O surf ace display a huge dependence on the polarization of the primary beam. Peak values of the spin asymmetries of the absorbed (reflected) current larger than 13% (45%) around 4-8 eV electron kinetic energy are obtained. The pres ence of the surface oxide protects the system against contamination, so tha t an almost negligible asymmetry deterioration is observed after prolonged operation in vacuum. The results are discussed in view of applications in e lectron spin polarimetry. (C) 1999 Elsevier Science B.V. All rights reserve d.