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

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(Φ), and power spectrum, F(ω), of the B flux rate Φ are measured under controlled values of the magnetization rate and differential permeability μ. It is found that all of the experimental data are approximately consistent with the law P0(Φ)∝Φ−1 exp(−Φ/〈Φ〉), where all dependencies on and μ are described by the single dimensionless parameter >0. Also the parameters describing the shape of F(ω) are found to obey remarkably simple and general laws of dependence on 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.