Magnonic Crystal with Two-Dimensional Periodicity as a Waveguide for Spin Waves

TL;DR

This paper presents a method to include dissipation in the spin wave band structure of 2D magnonic crystals, revealing directions and frequencies with significantly increased spin wave lifetimes, useful for waveguiding applications.

Contribution

It introduces a simple approach to account for damping in the band structure calculations of 2D ferromagnetic composites, highlighting potential for low-loss spin wave propagation.

Findings

Certain bands and directions exhibit over tenfold increased spin wave lifetime.

The method enables identification of frequencies and directions with minimal decay.

Potential for designing magnonic waveguides with enhanced propagation distances.

Abstract

We describe a simple method of including dissipation in the spin wave band structure of a periodic ferromagnetic composite, by solving the Landau-Lifshitz equation for the magnetization with the Gilbert damping term. We use this approach to calculate the band structure of square and triangular arrays of Ni nanocylinders embedded in an Fe host. The results show that there are certain bands and special directions in the Brillouin zone where the spin wave lifetime is increased by more than an order of magnitude above its average value. Thus, it may be possible to generate spin waves in such composites decay especially slowly, and propagate especially large distances, for certain frequencies and directions in ${\bf k}$-space.