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.