Microwave-assisted switching: Optimal microwave field for a nanomagnet with surface anisotropy

Abstract

We compute the optimal microwave field that induces the magnetization reversal of a nanomagnet modeled as a macrospin, while minimizing the total injected energy. Two complementary approaches, numerical and analytical, are presented. We then optimize the microwave field for a nanomagnet with a mixed uniaxial and cubic anisotropy. The optimal microwave fields are found to be modulated both in amplitude and frequency. We find that the cubic anisotropy, which is mainly due here to the surface contribution, has a major effect on the frequency profile, related to the variation of the effective field. © Published under licence by IOP Publishing Ltd.