Abstract
It is shown that gradual devitrification of non-magnetostrictive Co-based metallic glass leads to a giant, five orders of magnitude, increase of its coercivity. This magnetic hardening is due to the pinning by growing fine crystallites much smaller than the domain wall width, the number and size of which increase with an increase of the annealing temperature. It is also shown that FMR-technique is a very sensitive probe of microstructural changes in amorphous magnets.
