Dynamics of successive non-equilibrium transitions in thin-film ferromagnets
We show that in disordered ferromagnets, where magnetization reversal involves nucleation, domains’ expansion and annihilation, differences between the time dependencies of these processes are responsible for accumulation of the reversed nuclei, for the asymmetry of forward and backward magnetization reversals and for the respective cumulative growth of hysteresis loops. Presence of dilute enclaves of opposite magnetization within a magnetized ferromagnet can be detected by time and field dependent magnetization reversal. Such enclaves are stable due to dipolar fields generated by the surrounding material, and their presence at the onset of reversal can speed the process by orders of magnitude. The field required to suppress these nuclei and reach true magnetic saturation is found to be an order of magnitude higher than the observable macroscopic saturation field. Fatuzzo – Labrune model is extended to describe magnetization reversal starting with ready nucleation domains.