Statistical properties of Barkhausen noise in amorphous ferromagnetic films

TL;DR

This study analyzes the statistical properties of Barkhausen noise in amorphous ferromagnetic films, revealing a universal behavior consistent with three-dimensional domain wall dynamics and supporting a general scaling form for avalanche shapes.

Contribution

It provides the first comprehensive statistical analysis of Barkhausen noise in amorphous ferromagnetic films, establishing their universality class and confirming theoretical models of domain wall dynamics.

Findings

Films belong to a single universality class with specific scaling exponents.

Avalanche shapes depend on the universality class.

Results support a three-dimensional magnetic behavior with short-range interactions.

Abstract

We investigate the statistical properties of the Barkhausen noise in amorphous ferromagnetic films with thicknesses in the range between $100$ and $1000$ nm. From Barkhausen noise time series measured with the traditional inductive technique, we perform a wide statistical analysis and establish the scaling exponents $\tau$, $\alpha$, $1/\sigma \nu z$, and $\vartheta$. We also focus on the average shape of the avalanches, which gives further indications on the domain wall dynamics. Based on experimental results, we group the amorphous films in a single universality class, characterized by scaling exponents $\tau\sim 1.27$, $\alpha \sim 1.5$, $1/\sigma \nu z \sim \vartheta \sim 1.77$, values similar to that obtained for several bulk amorphous magnetic materials. Besides, we verify that the avalanche shape depends on the universality class. By considering the theoretical models for the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium found in literature, we interpret the results and identify an experimental evidence that these amorphous films, within this thickness range, present a typical three-dimensional magnetic behavior with predominant short-range elastic interactions governing the domain wall dynamics. Moreover, we provide experimental support for the validity of a general scaling form for the average avalanche shape for non-mean-field systems.