Barkhausen noise from formation of 360$^{\circ}$ domain walls in disordered permalloy thin films

TL;DR

This study uses micromagnetic simulations to reveal that Barkhausen noise in disordered permalloy thin films arises from the formation of immobile 360° domain walls, influenced by disorder strength.

Contribution

It uncovers a new mechanism involving 360° domain walls in magnetization reversal, expanding understanding beyond traditional domain wall motion.

Findings

Formation of immobile 360° domain walls during reversal

Disorder strength controls domain wall density

Statistical properties of Barkhausen jumps vary with disorder

Abstract

Barkhausen noise in disordered ferromagnets is typically understood to originate primarily from jerky field-driven motion of domain walls. We study the magnetization reversal process in disordered permalloy thin films using micromagnetic simulations, and find that the magnetization reversal process consists of gradual formation of immobile 360$^{\circ}$ domain walls via a sequence of localized magnetization rotation events. The density of 360$^{\circ}$ domain walls formed within the sample as well as the statistical properties of the Barkhausen jumps are controlled by the disorder strength.