Curvature-induced parity loss and hybridization of magnons: Exploring the connection of flat and tubular magnetic shells

TL;DR

This study investigates how curvature in magnetic shells affects magnon spectra, revealing curvature-induced parity loss and mode hybridization, with implications for designing magnetic devices.

Contribution

It introduces a numerical analysis of magnon spectrum evolution in curved magnetic shells, highlighting curvature-induced parity loss and mode hybridization mechanisms.

Findings

Curvature causes parity loss in higher-order magnon modes.

Curvature induces hybridization between orthogonal magnon modes.

Edge modes significantly influence the magnon spectrum in tubes.

Abstract

This paper delves into the connection between flat and curvilinear magnetization dynamics. For this, we numerically study the evolution of the magnon spectrum of rectangular waveguides upon rolling its cross-section up to a full tube. Magnon spectra are calculated over a wide range of magnetization states using a finite-element dynamic-matrix method, which allows us to trace the evolution of the magnon frequencies and several critical magnetic fields with increasing curvature. By analyzing the parity of the higher-order magnon modes, we find a curvature-induced mode hetero-symmetry that originates from a chiral contribution to the exchange interaction and is related to the Berry phase of magnons in closed loops. Importantly, this curvature-induced parity loss has profound consequences for the linear coupling between different propagating magnons, allowing for hybridization between initially orthogonal modes. In this context, we demonstrate the integral role of edge modes in forming the magnon spectrum in full tubes. Our findings provide new theoretical insights into curvilinear magnetization dynamics and are relevant for interpreting and designing experiments in the field.