Theory of magnon-skyrmion scattering in chiral magnets

TL;DR

This paper theoretically investigates how magnons scatter off skyrmions in chiral magnets, revealing deflection angles dependent on magnon wavelength and demonstrating momentum exchange that drives skyrmion motion.

Contribution

It provides a detailed theoretical analysis and micromagnetic simulations of magnon-skyrmion scattering, highlighting the momentum transfer mechanism and the non-Newtonian dynamics of skyrmions.

Findings

Magnons are deflected by skyrmions with angle depending on wavenumber.

Skyrmion motion is driven by magnon scattering via momentum exchange.

Total momentum of the system is conserved during scattering.

Abstract

We study theoretically the dynamics of magnons in the presence of a single skyrmion in chiral magnets featuring Dzyaloshinskii-Moriya interaction. We show by micromagnetic simulations that the scattering process of magnons by a skyrmion can be clearly defined although both originate in the common spins. We find that (i) the magnons are deflected by a skyrmion, with the angle strongly dependent on the magnon wavenumber due to the effective magnetic field of the topological texture, and (ii) the skyrmion motion is driven by magnon scattering through exchange of the momenta between the magnons and a skyrmion: the total momentum is conserved. This demonstrates that the skyrmion has a well-defined, though highly non-Newtonian, momentum.