Domain-wall dynamics and Barkhausen effect in metallic ferromagnetic materials. II. Experiments

Abstract

Barkhausen effect (BE) phenomenology in iron-based ferromagnetic alloys is investigated by a proper experimental method, in which BE experiments are restricted to the central part of the hysteresis loop, and the amplitude probability distribution, P0(Φ̇), and power spectrum, F(ω), of the B flux rate Φ̇ are measured under controlled values of the magnetization rate İ and differential permeability μ. It is found that all of the experimental data are approximately consistent with the law P0(Φ̇)∝Φ̇c̃−1 exp(−c̃Φ̇/〈Φ̇〉), where all dependencies on İ and μ are described by the single dimensionless parameter c̃>0. Also the parameters describing the shape of F(ω) are found to obey remarkably simple and general laws of dependence on İ and μ. The experimental results are interpreted by means of the Langevin theory of domain-wall dynamics proposed in a companion paper. The theory is in good agreement with experiments, and permits one to reduce the basic aspects of BE phenomenology to the behavior of two parameters describing the stochastic fluctuations of the local coercive field experienced by a moving domain wall.