Spin-wave spectral analysis in crescent-shaped ferromagnetic nanorods

TL;DR

This paper investigates how the geometry and magnetic field influence spin wave behavior in crescent-shaped ferromagnetic nanorods, revealing controllable nonreciprocal dispersion relations useful for magnonic devices.

Contribution

It introduces a numerical analysis of spin wave localization and dynamics in crescent-shaped nanostructures, highlighting the effects of geometry and magnetic field orientation.

Findings

Magnetic field direction breaks symmetry and alters eigenmode localization.

Field orientation affects spin wave frequency and saturation behavior.

Chirality-based nonreciprocal dispersion relations are controllable via field parameters.

Abstract

The research on the properties of spin waves (SWs) in three-dimensional nanosystems is an innovative idea in the field of magnonics. Mastering and understanding the nature of magnetization dynamics and binding of SWs at surfaces, edges, and in-volume parts of three-dimensional magnetic systems enables the discovery of new phenomena and suggests new possibilities for their use in magnonic and spintronic devices. In this work, we use numerical methods to study the effect of geometry and external magnetic field manipulations on the localization and dynamics of SWs in crescent-shaped (CS) waveguides. It is shown that changing the magnetic field direction in these waveguides breaks the symmetry and affects the localization of eigenmodes with respect to the static demagnetizing field. This in turn has a direct effect on their frequency. Furthermore, CS structures were found to be characterized by significant saturation at certain field orientations, resulting in a cylindrical magnetization distribution. Thus, we present chirality-based nonreciprocal dispersion relations for high-frequency SWs, which can be controlled by the field direction (shape symmetry) and its amplitude (saturation).