Imaging Collective Magnonic Modes in 2D Arrays of Magnetic Nanoelements

Abstract

We have used time resolved scanning Kerr microscopy to image collective spin wave modes within a 2D array of magnetic nanoelements. Long wavelength spin waves are confined within the array as if it was a continuous element of the same size but with effective material properties determined by the structure of the array and its constituent nanoelements. The array is an example of a magnonic metamaterial, the demonstration of which provides new opportunities within the emerging field of magnonics.

An effect of the curvature induced anisotropy on the spectrum of spin waves in a curved magnetic nanowire

“…[7][8][9][10][11] Recently there is a large number of works devoted to the study of one-and two-dimensional planar magnon crystals formed by periodic structuring of monolayer magnetic films, most often yttrium iron garnet 12,13 or transition metals. [14][15][16] However, since in the magnon devices the topology is essential, it is necessary to study properties of connections between different parts of structural elements of magnonic devices and metamaterials. This gives rise to the renewed interest in the theoretical study of curved low-dimensional systems.…”

Asymmetry of spin wave dispersions in a hexagonal magnonic crystal

“…3,5,9,10 Dense arrays of in-plane magnetized nano-disks have been extensively investigated by ferromagnetic resonance, [11][12][13][14][15] Brillouin light scattering (BLS), [16][17][18][19][20][21][22][23] and time resolved magneto-optical measurements. [24][25][26][27][28] However, arrays of disks arranged into a hexagonal mesh have been sparsely studied so far, and the experimental data have been presented for wave vector k ¼ 0 only. 29 This is probably due to the fact that arrays of disks arranged in the hexagonal symmetry are challenging not only from the fabrication and characterization perspective but also from the point of view of their theoretical modeling.…”

“…29 This is probably due to the fact that arrays of disks arranged in the hexagonal symmetry are challenging not only from the fabrication and characterization perspective but also from the point of view of their theoretical modeling. 6,8,9,11,24,25,30,31 In this work, we study the dispersion of collective SWs in the Voigt scattering geometry in a hexagonal array of 20 nm thick Permalloy (Ni 80 Fe 20 ) disks for two different directions of the applied magnetic field and therefore SW propagation. We find that equivalent modes in equivalent scattering geometries have different dispersive behavior ("asymmetry") along the two principal directions of the lattice.…”

Large amplitude magnetization dynamics and the suppression of edge modes in a single nanomagnet

“…Most dynamical studies have been performed on arrays of nanomagnets 1,2 where interelement dipolar interactions can lead to collective excitations [3][4][5][6] while structural variations lead to inhomogeneous broadening.…”

“…12 A 440 nm square with rounded corners of radius 55 nm was modeled as a single layer using a mesh of cell size 4 ϫ 4 ϫ 7 nm 3 and an exchange parameter of 13ϫ 10 −7 ergs/ cm. Simulations with smaller cell sizes did not show any significant differences.…”