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.

Magnetic Vortices in Ferromagnetic Nanodots

“…In particular, the mechanism of creating the vortex-antivortex pair is still unclear. In addition, it is interesting to clarify the character of the nonlinear magnetic vortex oscillation and the effect of the magnetostatic interaction between nanodots in array on the oscillation modes [47][48][49][50][51].…”

Simultaneous control of magnetic topologies for reconfigurable vortex arrays

“…1,2 Because both circularity and polarity can be specified by two independent values, that is, c = ± 1 and p = ± 1, four distinct spin states can exist in a single magnetic element with the combination of circularity and polarity. Magnetic vortices have been intensively studied due to their compelling physical behavior [3][4][5][6][7] and their potential in a wide range of applications such as data storage, 8,9 signal transfer, [10][11][12] logic devices, 13 transistors 14 and artificial skyrmion crystals. [15][16][17][18] With respect to practical application of magnetic vortices in advanced nanotechnologies, one of the critical factors is the effective reconfigurability of two topologies, c and p, particularly within large and densely packed arrays of magnetic elements.…”

“…19,20 As a representative example, for successful achievement of vortex-based signal transfer and logic and transistor operations, the desired configurations of magnetic vortex states must be first established. [10][11][12][13][14] Additionally, uniformly arranged vortex structures are also required to generate artificial skyrmion crystals based on magnetic vortices in proximity to perpendicularly magnetized thin films. [15][16][17][18] For effective reconfiguration of magnetic vortex structures, one key issue is reliable and efficient control of both c and p in magnetic vortices, which is also vital for storage applications.…”

Burst-mode manipulation of magnonic vortex crystals

“…Coupling occurs when the center-to-center distance of a pair of vortices is less than twice the diameter of the disks [8,9]. The interaction between the elements has been studied for pairs [10][11][12], chains [13], and two-dimensional arrangements [14][15][16] of vortices. In contrast to systems of coupled harmonic oscillators, the interaction strength can be tuned dynamically, in dependence on the polarizations [11,[17][18][19].…”