Amorphous alloys as secondary standards for electron spin polarimetry

The surface magnetism of as-cast and field annealed amorphous Co66Fe4Ni1B14 Si15 in ribbon form has been studied by spin-polarized secondary electron s pectroscopy, by recording energy-resolved spin asymmetry hysteresis loops a nd by scanning electron microscopy with polarization analysis. Large latera l variations in surface magnetization have been detected, indicating that C o66Fe4Ni1B14Si15, in particular and ferromagnetic melt-spun ribbons, in gen eral, are not suitable as standard sources of polarized electrons. Depositi on of an iron film onto the Co66Fe4Ni1B14Si15 did not result in a more unif orm surface but rather served to emphasize the substrate magnetic structure . Thus utilization of ferromagnetic melt-spun amorphous alloys as substrate s for the growth of thin magnetic films should be undertaken with caution.