Indirect switching of vortex polarity through magnetic dynamic coupling

TL;DR

This paper investigates how vortex core polarity can be switched indirectly through magnetic dynamic coupling in nanodisks, revealing the influence of perpendicular anisotropy and non-local excitation on the reversal process.

Contribution

It demonstrates that vortex polarity reversal depends on perpendicular anisotropy and can be achieved non-locally via dynamic coupling between disks, challenging universal criteria based solely on exchange stiffness.

Findings

Critical velocity decreases with increasing perpendicular anisotropy.

Vortex core radius inversely affects the critical velocity.

Polarity can be switched in a neighboring disk through non-local excitation.

Abstract

Magnetic vortex cores exhibit a gyrotropic motion, and may reach a critical velocity, at which point they invert their z-component of the magnetization. We performed micromagnetic simulations to describe this vortex core polarity reversal in magnetic nanodisks presenting a perpendicular anisotropy. We found that the critical velocity decreases with increasing perpendicular anisotropy, therefore departing from a universal criterion, that relates this velocity only to the exchange stiffness of the material. This leads to a critical velocity inversely proportional to the vortex core radius. We have also shown that in a pair of interacting disks, it is possible to switch the core vortex polarity through a non-local excitation; exciting one disk by applying a rotating magnetic field, one is able to switch the polarity of a neighbor disk, with a larger perpendicular anisotropy.