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 annealing at 600 degrees C produces a well-ordered p(1 x 1) overlayer. The low energy electron absorption and reflection from the Fe(001)-p(1 x 1)O surface 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 presence of the surface oxide protects the system against contamination, so that an almost negligible asymmetry deterioration is observed after prolonged operation in vacuum. The results are discussed in view of applications in electron spin polarimetry. (C) 1999 Elsevier Science B.V. All rights reserved.