POTENTIAL-SHAPE EFFECTS IN SPLEED FROM FERROMAGNETS

A fully relativistic theory of spin-polarized low-energy electron diffraction (SPLEED) from ferromagnets, which allows for non-spherical effective potentials and magnetic fields, is applied to the Fe (110) surface. Non-muffin-tin corrections turn out to produce some noticeable spectral changes. However, they do not affect a peak in the exchange scattering asymmetry, which is very sensitive to the assumed magnetic moment of the topmost layer. This peak is, however, significantly enhanced if one replaces the conventional form of the spherical magnetic field in the surface layer by a form close to that obtained in a slab ground state calculation. This implies a modification of a previous SPLEED analysis such that the magnetization of the topmost layer of Fe (110) is enhanced only by about 30 to 35% relative to the bulk.