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

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.