Microwave assisted switching mechanism and its stable switching limit

Abstract

Microwave assisted switching (MAS) of magnetization has been intensively studied as an alternative technique for ultrahigh density magnetic recording. In this paper, comparison between the Landau–Lifshitz–Gilbert simulation and the analytical model in the rotating frame {Bertotti et al., [Phys. Rev. Lett. 86, 724 (2001)]} reveals that the switching behaviors of MAS can be clearly divided into two groups, that is, stable and unstable switching regions, depending on the frequency and amplitude of the ac field. The stable switching exhibits small switching field and narrow switching field distribution, and perfectly coincides with by the analytical model. Furthermore, in this region, the Sharrock type thermal fluctuation formula can be applicable to the MAS at finite temperature. On the other hand, for the unstable switching, the switching field is rather large and the SDF becomes very broad. Obviously, the former is preferable for the practical application of MAS. The critical frequency of the ac field for the limit of stable switching is almost proportional to the ac field amplitude.