Controlling the Suhl Instability in Magnetic Nanoparticles: A Numerical Study

Non-linear excitation of non-uniform spin waves (Suhl instability) is of profound importance when it comes to magnetization reversal using r.f. fields. Here we numerically show 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 wave eigenfunctions.