A topological gauge field in nanomagnets: spin wave excitations over a slowly moving magnetization background

TL;DR

This paper introduces a topological gauge vector potential affecting spin wave excitations in nanomagnets with non-uniform, slowly moving magnetization, revealing significant effects on vortex-spin wave interactions and mode frequencies.

Contribution

It presents a novel topological gauge field framework to describe spin wave dynamics over moving magnetization backgrounds in nanostructures.

Findings

Giant frequency splitting of spin wave modes due to vortex interaction

Finite vortex mass of dynamical origin identified

Gauge field approach explains vortex-spin wave coupling

Abstract

We introduce a topological gauge vector potential which influences spin wave excitations over arbitrary non-uniform, slowly moving magnetization distribution. The time-component of the gauge potential plays a principal role in magnetization dynamics, whereas its spatial components can be often neglected for typical magnetic nanostructures. As an example, we consider spin modes excited in the vortex state magnetic dots. It is shown that the vortex/ spin wave interaction can be described as a consequence of the gauge field arising due to non uniform moving vortex magnetization distribution. The coupled equations of motion of the vortex and spin waves are solved within small excitation amplitude approximation. The model yields a giant frequency splitting of the spin wave modes having non-zero overlapping with the vortex mode as well as a finite vortex mass of dynamical origin.