Shape anisotropy effect on magnetization reversal induced by linear down chirp pulse

Z. K. Juthy, M. A. J. Pikul, M. A. S. Akanda, M. T. Islam

Published 2021-08-24Version 1

We investigate the influence of shape anisotropy on the magnetization reversal of a single-domain magnetic nanoparticle driven by a circularly polarized linear down-chirp microwave field pulse (DCMWP). Based on the Landau-Lifshitz-Gilbert equation, numerical results show that the three controlling parameters of DCMWP, namely, microwave amplitude, initial frequency and chirp rate, decrease with the increase of shape anisotropy. These findings are related to the effective anisotropy and thus to the height energy barrier which separates the two stable states. The result of damping dependence of magnetization reversal indicates that for a certain sample shape, there exists an optimal damping situation at which magnetization is fastest. Moreover, it is also shown that the required microwave field amplitude can be lowered by applying the spin-polarized current simultaneously. The usage of an optimum combination of both microwave field pulse and current is suggested to achieve cost efficiency and faster switching. So these findings may provide the knowledge to fabricate the shape of a single domain nanoparticle for the fast and power-efficient magnetic data storage device.