Nontrivial Aharonov-Bohm effect and alternating dispersion of magnons in cone-state ferromagnetic rings

TL;DR

This paper explores the topological Aharonov-Bohm effect in magnon modes within cone-state ferromagnetic rings, revealing giant mode splitting and non-monotonic frequency dependence due to magnetic topology and interactions.

Contribution

It introduces an analytical and numerical study of magnon modes in magnetic rings, highlighting a magnon analog of the Aharonov-Bohm effect caused by topology.

Findings

Giant splitting of magnon doublets in magnetic rings.

Non-monotonic dependence of mode frequencies on azimuthal quantum number.

Development of an analytical theory explaining the mode behavior.

Abstract

Soft magnetic dots in the form of thin rings have unique topological properties. They can be in a vortex state with no vortex core. Here, we study the magnon modes of such systems both analytically and numerically. In an external magnetic field, magnetic rings are characterized by easy-cone magnetization and shows a giant splitting of doublets for modes with the opposite value of the azimuthal mode quantum number. The effect of the splitting can be refereed as a magnon analog of the topology-induced Aharonov-Bohm effect. For this we develop an analytical theory to describe the non-monotonic dependence of the mode frequencies on the azimuthal mode number, influenced by the balance between the local exchange and non-local dipole interactions.