Amorphous alloys as secondary standards for electron spin polarimetry

The surface magnetism of as-cast and field annealed amorphous Co\+v\66\-v\Fe\+v\4\-v\Ni\+v\1\-v\B\+v\14\-v\Si\+v\15\-v\ in ribbon form has been studied by spin-polarized secondary electron spectroscopy, by recording energy-resolved spin asymmetry hysteresis loops and by scanning electron microscopy with polarization analysis. Large lateral variations in surface magnetization have been detected, indicating that this material in particular, and ferromagnetic melt spun ribbons in general, are not suitable as standard sources of polarized electrons. Deposition of an iron film did not result in a more uniform surface but rather served to emphasize the substrate magnetic structure. (Original abstract - amended)