Nonuniversal scaling behavior of Barkhausen noise

TL;DR

This paper investigates the nonuniversal scaling behavior of Barkhausen noise through simulations of avalanches in a disordered ferromagnet, revealing how critical exponents depend on disorder and driving rate.

Contribution

It introduces a model simulating Barkhausen avalanches on fractal clusters, demonstrating nonuniversal scaling exponents influenced by disorder and driving rate.

Findings

Scaling region identified for moderate disorder

Exponents vary with disorder and driving rate

Scaling relation between exponents confirmed

Abstract

We simulate Barkhausen avalanches on fractal clusters in a two-dimensional diluted Ising ferromagnet with an effective Gaussian random field. We vary the concentration of defect sites $c$ and find a scaling region for moderate disorder, where the distribution of avalanche sizes has the form $D(s,c,L) = s^{-(1+\tau (c))}{\cal{D}}(sL^{-D_s(c)})$. The exponents $\tau (c)$ for size and $\alpha (c)$ for length distribution, and the fractal dimension of avalanches $D_s(c)$ satisfy the scaling relation $D_s(c)\tau (c) =\alpha (c)$. For fixed disorder the exponents vary with driving rate in agreement with experiments on amorphous Si-Fe alloys.