Quantitative Scaling of Magnetic Avalanches

We provide the first quantitative comparison between Barkhausen-noise experiments and recent predictions from the theory of avalanches for pinned interfaces, both in and beyond mean-field. We study different classes of soft magnetic materials: polycrystals and amorphous samples, characterized by long-range and short-range elasticity, respectively; both for thick and thin samples, i.e. with and without eddy currents. The temporal avalanche shape at fixed size, and observables related to the joint distribution of sizes and durations are analyzed in detail. Both long-range and short-range samples with no eddy currents are fitted extremely well by the theoretical predictions. In particular, the short-range samples provide the first reliable test of the theory beyond mean field. The thick samples show systematic deviations from the scaling theory, providing unambiguous signatures for the presence of eddy currents.
v1: 5 pages, 6 figures; Supplemental Materials, 5 pages, 6 figures. v2+v3: updated version as published in PRL. v3: 8 pages, 12 figures. v3 corrects errors induced by a bug in assembling the pdf-files