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

TL;DR

This paper models microwave-assisted magnetisation reversal in micron-sized magnetic ellipsoids, showing it requires less field than static reversal and involves complex oscillating switching times influenced by spinwave instabilities and domain wall dynamics.

Contribution

It introduces a detailed simulation model for microwave-assisted switching in magnetic ellipsoids, highlighting the distinct reversal mode and complex frequency dependence.

Findings

Microwave-assisted reversal requires less magnetic field than static reversal.

Reversal involves a ripple mode and two stages: nucleation and relaxation.

Switching time oscillates with microwave frequency due to spinwave and domain wall dynamics.

Abstract

The microwave assisted magnetisation reversal is modelled in a permalloy micron-sized magnetic ellipsoid. Our simulations confirm that this process requires less field than magnetisation reversal under a static field. This is due to a different reversal mode which in case of the microwave-assisted process is always a ripple structure. During the magnetisation reversal two stages: nucleation and relaxation are distinguished. The nucleation process is governed by spinwave 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.