Modeling of microwave-assisted switching in micron-sized magnetic ellipsoids

The microwave-assisted magnetization reversal is modeled in a permalloy micron-sized magnetic ellipsoid. Our simulations confirm that this process requires less field than magnetization reversal under a static field. This is due to a different reversal mode which in the case of the microwave-assisted process is always a ripple structure. During the magnetization reversal, two stages, nucleation and relaxation, are distinguished. The nucleation process is governed by spin-wave instabilities. The relaxation process is related to the domain expansion through domain-wall propagation determined by the precessional motion of magnetic moments in the center of the domain walls. As a consequence, the switching time is a complex oscillating function of the microwave frequency.