Universality and the collapse of multifractality in Barkhausen avalanches

TL;DR

This paper investigates the multifractal properties of Barkhausen avalanches in ferromagnetic films, revealing a universal transition from multifractal to monofractal behavior as film thickness decreases, linked to a dimensional change in magnetic dynamics.

Contribution

It introduces the first observation of the collapse of multifractality in Barkhausen avalanches, connecting it to a universal dimensional transition in magnetic domain wall dynamics.

Findings

Multifractal properties depend on film thickness.

Multifractality collapses as thickness decreases.

Transition from 3D to 2D magnetic behavior observed.

Abstract

Barkhausen effect in ferromagnetic materials provides an excellent area for investigating scaling phenomena found in disordered systems exhibiting crackling noise. The critical dynamics is characterized by random pulses or avalanches with scale-invariant properties, power-law distributions, and universal features. However, the traditional Barkhausen avalanches statistics may not be sufficient to fully characterize the complex temporal correlation of the magnetic domain walls dynamics. Here we go beyond power laws and focus on the multifractal scenario to quantify the temporal scaling characteristics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films with thicknesses from $50$ nm to $1000$ nm. We show that the multifractal properties are dependent on the film thickness, and insensitive to the structural character of the materials. Further, we observe for the first time the collapse of the multifractality in the domain walls dynamics as the thickness is reduced, and the multifractal behavior gives place to a monofractal one over the entire range of time scales. The reorganization in the temporal scaling characteristics of Barkhausen avalanches is understood as an universal restructuring associated to the dimensional transition, from three to two-dimensional magnetization dynamics.