Anomalous Barkhausen noise produced by the magnetic aftereffect in ferromagnetic amorphous ribbons

It has been shown that the presence of a magnetic aftereffect in amorphous ferromagnets is the origin of an anomalous Barkhausen (B.) noise. Experiments on commercial Metglas 2605 SC and 2605 CO alloys have evidenced an increment of the power spectrum of the noise of up to two orders of magnitude. This fact has been interpreted as due to the competitive effect between the onset of a viscosity field and the growth of the driving field acting on a wall after its arrest at the end of a large B. discontinuity. In the present paper experiments on the anomalous B. noise are extended to higher temperatures and the excess noise generated by the magnetic aftereffect evaluated on the basis of viscosity field measurements done on the same specimens. This allows us to check and improve a theoretical model presented in a previous paper.