Spin waves in planar quasicrystal of Penrose tiling

Abstract

We investigated two-dimensional magnonic structures which are the counterparts of photonic quasicrystals forming Penrose tiling. We considered the slab composed of Ni (or Py) disks embedded in Fe (or Co) matrix. The disks were arranged in quasiperiodic Pernose-like structure. The infinite quasicrystal was approximated by its rectangular section with periodic boundary conditions applied. This approach allowed us to use the plane wave method to find the frequency spectrum of eigenmodes for spin waves and their spatial profiles. The calculated integrated density of states shows more distictive magnonic gaps for the structure composed of materials of high magnetic contrast (Ni and Fe) and relatively high filling fraction. This proves the impact of quasiperiodic long-range order on the spectrum of spin waves. We also investigated the localization of SW eingenmodes resulting from the quasipeiodicity of the structure.

Direct Observation of Worm‐Like Nanochannels and Emergent Magnon Motifs in Artificial Ferromagnetic Quasicrystals

“…Relaxing the condition of periodicity allows one to directly probe the effect of aperiodicity on such type of patterns and explore their possible application (as reported in this article) due to increased spatial and rotational degrees of freedom. In contrast to photonics and plasmonics, [ 10–12 ] experimental studies on artificial ferromagnetic quasicrystals (AMQs) [ 28 ] which offer unconventional rotational symmetries and a great density of reciprocal vectors are in their infancy. [ 21,29,30 ] Corresponding dynamic magnetic responses in 2D quasicrystals have neither been classified nor fully exploited in view of manipulation and control of magnons.…”

Controlling the three dimensional propagation of spin waves in continuous ferromagnetic films with an increasing out of plane undulation

“…In the last decades, the conceptual problem was just studying SW propagation, which is inherently a two-dimensional problem, since a signal travelling along a waveguide can be embedded in one- (1D) or two-dimensional (2D) space, depending on the curvature 5 – 9 . Hence, the research exploration has mainly involved structures displaying 1D/2D magnetization textures, either periodic 10 – 13 or aperiodic 14 – 17 , while structures with in-plane periodicity, but inhomogeneous along the perpendicular direction, have been poorly explored so far. However, exploring the third dimension is crucial indeed, because a 3D distribution of the magnetization offers a new degree of freedom, which in general allows, from one side, to fit more functionality into a smaller space, and hence to considerably increase the density of elements in magnonic devices 18 , 19 , and from the other, further possibilities for the SW dynamics and transport (e.g., vertical magnon transport, nonreciprocal coupling 20 – 22 ).…”

A modal approach to modelling spin wave scattering

“…Spectral methods enable calculation of the response of a magnetic system to a time-harmonic excitation with high precision and at a lower computational cost, though at the price of approximations, one of which is linearisation. For systems with discrete translational symmetry, the plane wave method was introduced and used to calculate the band structure in bulk [24] and thinfilm magnonic crystals [25][26][27], as well as magnonic quasicrystals [28,29]. In the latter case, a full magnetic saturation and homogeneity across the film thickness were assumed.…”