Power laws, flicker noise, and the Barkhausen effect

The Barkhausen effect was studied in three ferromagnetic metals: an amorphous alloy, iron, and alumel. The data exhibit all the characteristics of self-organized critical behavior enumerated by Bak, Tang, and Wiesenfeld: The distributions of pulse durations, areas, and energies have the form of power laws, which have been modified to account for finite-size effects as suggested by Kadanoff, Nagel, Wu, and Zhou, and the power spectral densities have the form of flicker noise. Furthermore, the parameters describing the Barkhausen noise pulse distributions are consistent with those characterizing the power spectral density in the light of the results of Jensen, Christensen, and Fogedby. The data are also consistent with a model based on an inherent static fractal structure, independent of a self-organizing principle.