Low-amplitude magnetic vortex core reversal by non-linear interference between azimuthal spin waves and the vortex gyromode

TL;DR

This paper demonstrates that simultaneous excitation of vortex gyromode and spin waves in ferromagnetic microplates causes non-linear interference, significantly reducing the magnetic field needed for vortex core reversal and revealing new resonance phenomena.

Contribution

It introduces a novel dual-frequency excitation method that enhances vortex core reversal efficiency and uncovers new resonance effects due to non-linear interference.

Findings

Reduced vortex core reversal threshold by nearly tenfold

Discovery of new spin wave resonance frequencies

Confirmation of non-linear interference effects through experiments and simulations

Abstract

We demonstrate a non-linear interference due to an active 'dual frequency' excitation of both, the sub-GHz vortex gyromode and multi-GHz magneto-static spin waves in ferromagnetic micrometer sized platelets in the vortex state. When the sub-GHz vortex gyromode is excited simultaneously a significant broadband reduction of the switching threshold for spin wave mediated vortex core reversal is observed in both, experiments and micromagnetic simulations. Consequently, the magnetic field amplitudes required for vortex core reversal can be lowered by nearly one order of magnitude. Moreover, additional spin wave resonance frequencies are found which emerge only if the vortex gyromode is actively excited simultaneously which can be explained by frequency doubling and by the broken symmetry of the vortex state.