Effects of applied stress on the complex permeability spectra in amorphous ribbons with positive and negative magnetostriction

The dependence of complex permeability spectra on applied tensile stress a were measured for Fe and Co based amorphous ribbons with positive and negative magnetostriction, respectively. The permeability spectra for .both ribbons at a = 0 showed typical two relaxation dispersions, one is the relaxation originating from reversible magnetization process and the other is that from the irreversible relaxation. For the Fe based ribbon, the contribution from the reversible relaxation to the permeability spectrum became negligible as σ increases and then the irreversible relaxation became dominant. However, there was an opposite stress dependence for Co based ribbons. The stress dependence of the spectra indicates that the magnetization rotation and domain wall displacement are the mechanisms responsible for the reversible and irreversible relaxation in the permeability spectra for amorphous ribbons, respectively.