title: Wave modes of collective vortex gyration in dipolar-coupled-dot-array 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) periodic arrays of magnetic 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 arrays. 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.
authors.affiliation: National Creative Research Initiative Center for Spin Dynamics and Spin-Wave Devices, Nanospinics Laboratory, and Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, Republic of Korea.
authors.forename: Dong-Soo
authors.initials: DS
authors.lastname: Han
authors.forename: Andreas
authors.initials: A
authors.lastname: Vogel
authors.forename: Hyunsung
authors.initials: H
authors.lastname: Jung
authors.forename: Ki-Suk
authors.initials: KS
authors.lastname: Lee
authors.forename: Markus
authors.initials: M
authors.lastname: Weigand
authors.forename: Hermann
authors.initials: H
authors.lastname: Stoll
authors.forename: Gisela
authors.initials: G
authors.lastname: Schütz
authors.forename: Peter
authors.initials: P
authors.lastname: Fischer
authors.forename: Guido
authors.initials: G
authors.lastname: Meier
authors.forename: Sang-Koog
authors.initials: SK
authors.lastname: Kim