Energy landscape and thermally activated switching of submicron-sized ferromagnetic elements

Thermally activated switching and the energy landscape of submicron-sized magnetic elements are studied using the string method. For thin films, we found that switching proceeds by two generic scenarios: Domain-wall propagation and reconnection followed by edge domain switching, or vortex nucleation at the boundary followed by vortex propagation through the sample. The second scenario is preferred for thicker films whereas the first is preferred for thin (less than 20 nm) films. The energy landscape of such a system is nicely summarized on the plane spanned by the average magnetization in the in-plane directions. For three-dimensional samples, we found that switching proceeds by vortex propagation through the sample. The implication of the Landau–Lifshitz dynamics is also discussed.