An optical method to study the domain wall dynamic instability in amorphous ribbons

An original method for the determination of the surface energy gamma /sub 0/ of a Bloch wall in a ferromagnetic specimen characterized by an antiparallel domain structure is described. It is based on the fact that, when the wall is oscillating with an increasing amplitude under the action of an external field, a critical amplitude is reached above which the wall becomes unstable and wall multiplication takes place. For a given frequency, the critical amplitude depends on the value of gamma /sub 0/. The mathematical procedure for determining the relation between the critical oscillation amplitude and gamma /sub 0/ is described and tested on a set of experimental results obtained on a specimen of Metglas 2605 SC. The wall oscillation amplitude is measured by means of an optical setup.<
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