Controlling the Suhl instability: a numerical study

TL;DR

This study numerically demonstrates that the Suhl instability in magnetization switching can be suppressed by tuning the applied field and sphere size to avoid resonant excitation of spin waves, offering a potential way to improve magnetic switching efficiency.

Contribution

It introduces a numerical method to suppress the Suhl instability by selecting field and size parameters that detune resonant spin wave modes.

Findings

Suhl instability can be suppressed by off-resonance mode excitation.

Mode projection explains the suppression mechanism.

Results are specific to spherical geometries.

Abstract

Magnetization reversal (switching) using either r.f. fields or brute-force precessional switching is currently thought to ultimately be limited by the non-linear excitation of non-uniform spin waves, the so-called Suhl instability. Here we show (numerically, for the case of a sphere) that this instability can be suppressed by choosing the applied field and/or sphere diameter in such a way that the frequencies of the modes that can be excited through non-linear processes are off-resonance. While the results cannot be explained by a traditional model based on plane waves, they can be understood by projecting the actual state onto the small amplitude spin resonant eigenfunctions.