Signature of effective mass in crackling noise asymmetry

TL;DR

This paper links the asymmetry in crackling noise pulses, specifically in the Barkhausen effect, to the negative effective mass of magnetic domain walls, offering new insights into the inertial origins of noise asymmetries.

Contribution

It demonstrates that the leftward asymmetry in Barkhausen noise is caused by the negative effective mass of domain walls, providing a novel inertial explanation for crackling noise asymmetries.

Findings

Asymmetry in Barkhausen noise is due to negative effective mass.

Effective mass can be inferred from noise pulse shapes.

Inertia explains avalanche asymmetries in crackling noise.

Abstract

Crackling noise is a common feature in many dynamic systems [1-9], the most familiar instance of which is the sound made by a sheet of paper when crumpled into a ball. Although seemingly random, this noise contains fundamental information about the properties of the system in which it occurs. One potential source of such information lies in the asymmetric shape of noise pulses emitted by a diverse range of noisy systems [8-12], but the cause of this asymmetry has lacked explanation [1]. Here we show that the leftward asymmetry observed in the Barkhausen effect [2] - the noise generated by the jerky motion of domain walls as they interact with impurities in a soft magnet - is a direct consequence of a magnetic domain wall's negative effective mass. As well as providing a means of determining domain wall effective mass from a magnet's Barkhausen noise our work suggests an inertial explanation for the origin of avalanche asymmetries in crackling noise phenomena more generally.