  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.
