Spin wave dynamics in two- and three-dimensional superlattices of nanosized ferromagnetic spheres

Abstract

The dispersion of spin wave modes which due to the dipolar interactions propagate along different directions of ordered superlattices of nanospheres is investigated. For this purpose a procedure similar to the well-known method of linear combination of atomic orbitals is applied. Different geometries of two-dimensional (triangular and square) and three-dimensional (simple cubic and hexagonal-close-packed) arrangements are considered and the influence of dimensionality on the spin wave dynamics is analyzed. A phase transition which is caused by the competition between dipolar and uniaxial anisotropy interactions is predicted by the investigation of the dispersion of the uniform Kittel mode for the superlattice of the hexagonal order. In conclusion, it is shown how the weak dipolar interaction enhances or decreases the relaxation time in the samples with a controlled direction of the easy axis.

Large magnonic band gaps and spectra evolution in three-dimensional magnonic crystals based on magnetoferritin nanoparticles

“…53,54 Neither have 3D MCs been realized experimentally, and remain the subject of theoretical studies. [54][55][56][57][58] The protein crystallization technique discussed above seems to open the prospect of realizing 3D MCs with a lattice constant of ten-odd nanometers. This would be an enormous step forward in magnonics, and would allow us to shift the magnonic band gap to the subterahertz frequency range.…”

Magnetodynamical response of large-area close-packed arrays of circular dots fabricated by nanosphere lithography

“…Nonetheless, it might be tempting to apply some kind of analytical or semi-analytical theory (see, e.g., Refs. [40][41][42][43][44] to draw conclusions more general than those presented here based on the micromagnetic simulations (at least at the larger bias field values). However, although such theories have an inherent advantage over simulations by facilitating a simpler generalization, this advantage quickly diminishes as the complexity of the observed phenomena increases.…”

“…Theoretical analysis of the magnetization dynamics in arrays of thin magnetic nanoelements is highly complicated both due to the long-range character of the magnetodipolar interaction and the possibly inhomogeneous magnetization ground state of such nanoelements. Neglecting the letter complication (i.e., assuming that all elements are in a magnetically saturated state), corresponding theoretical description of the spin-wave spectrum could be developed for 2D and 3D arrays of spherical particles 40 and 2D arrays of thin-film elements having a rectangular lateral shape. 41 The semianalytical approach developed in Ref.…”

Spectrum and reflection of spin waves in magnonic crystals with different interface profiles

“…This is mainly due to the complicating role of the long rage magnetodipole interaction, combined with the increased number of material parameters that affect the dispersion of magnons in such media. The situation is even more complicated in the case of 2D and 3D magnonic crystals, for which only few theoretical results have been published so far, [10][11][12][13] with strong approximations often made. Alternatively, the spectra of spin waves in magnonic crystals can be obtained from micromagnetic simulations ͑with only 1D case having been considered to date 18,19 ͒, or using the dynamical-matrix method, 20 which can be thought of as micromagnetics in the reciprocal space.…”

“…The study of spin waves and magnonic crystals ͑so-called "magnonics"͒ has been intensively growing recently as a new research field at the interface between nanomagnetism and electromagnetic metamaterials. So, many exciting results have recently been obtained in magnonics by experimental, [4][5][6][7][8][9] theoretical, [10][11][12][13][14][15][16][17] and computational [18][19][20] means.…”