Wave modes of collective vortex gyration in dipolar-coupled-dot-array magnonic crystals

TL;DR

This paper experimentally observes and analyzes wave modes of collective vortex gyration in 1D chains of magnetic disks, revealing how vortex properties influence mode dispersion, with implications for magnonic crystal applications.

Contribution

It provides the first experimental observation of vortex gyration wave modes in 1D magnetic disk arrays and links mode dispersion to vortex polarization and chirality.

Findings

Wave modes are experimentally observed in 1D vortex arrays.

Mode dispersion is strongly affected by vortex polarization and chirality.

The study offers insights for designing magnetic magnonic crystals.

Abstract

Lattice vibration modes are collective excitations in periodic arrays of atoms or molecules. These modes determine novel transport properties in solid crystals. Analogously, in periodical arrangements of magnetic vortex-state disks, collective vortex motions have been predicted. Here, we experimentally observe wave modes of collective vortex gyration in one-dimensional (1D) chains of periodic disks using time-resolved scanning transmission x-ray microscopy. The observed modes are interpreted based on micromagnetic simulation and numerical calculation of coupled Thiele equations. Dispersion of the modes is found to be strongly affected by both vortex polarization and chirality ordering, as revealed by the explicit analytical form of 1D infinite chains. A thorough understanding thereof is fundamental both for lattice vibrations and vortex dynamics, which we demonstrate for 1D magnonic crystals. Such magnetic disk arrays with vortex-state ordering, referred to as magnetic metastructure, offer potential implementation into information processing devices.