J. Rychły, S. Mieszczak, J.W. Kłos     
J. Magn. Magn. Mater. 450, 18 (2018)    

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 are arranged in quasiperiodic Penrose-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 distinctive 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 spin wave eingenmodes resulting from the quasiperiodicity of the structure.

Fig.1. The Penrose P3 tiling in the form of rosette of 5-fold symmetry. The considered magnonic structure consists of Ni (or Py) disks of diameter 5.6 nm embedded in Fe (or Co) slab of the same thickness. The disks are placed in the centers of Penrose tiles: wide (blue) and narrow (green) rhombus.

Y. Dadoenkova, N. Dadoenkova, M. Krawczyk, and I. Lyubchanskii     
Opt. Lett. 43, 3965 (2018)

The lateral shift of an optical beam undergoing Brillouin light scattering on an acoustic wave (AW) in the total internal reflection geometry is studied theoretically. It is shown that the lateral shift depends on polarization (longitudinal or transversal) of the AW, as well as on the type of scattering process: a direct one, when the scattered wave undergoes a lateral shift at reflection from the interface, or a cascading one, when a fundamental frequency light beam is laterally shifted at reflection and then scattered on the AW.

Fig.1. Schematics of the direct (a) and cascade (b) BLS processes. Here s and p denote s- and p-polarized light, ω and Ω are the fundamental light frequency and frequency of the AW, and ΔS is the GH shift.

P. Gruszecki, M. Mailyan, O. Gorobets, and M. Krawczyk     
Phys. Rev. B 95, 014421 (2017)    

The main object of investigation inmagnonics, spin waves (SWs) are promising information carriers. Presently, the most commonly studied are plane-wave-like SWs and SWs propagating in confined structures, such as waveguides. Here we consider a Gaussian SW beam obliquely incident on an ultranarrow interface between two identical ferromagnetic materials. We use an analytical model and micromagnetic simulations for an in-depth analysis of the influence of the interface properties, in particular the magnetic anisotropy, on the transmission of the SW beam. We derive analytical formulas for the reflectance, transmittance, phase shift, and Goos-Hanchen (GH) shift for beams reflected and refracted by an interface between two semi-infinite ferromagnetic media. The GH shifts in SW beam reflection and transmission are confirmed by micromagnetic simulations in the thin-film geometry. We demonstrate the dependence of the characteristic properties on the magnetic anisotropy at the interface, the angle of incidence, and the frequency of the SWs. We also propose a method for the excitation of high-quality SW beams in micromagnetic simulations.

Fig.1. Schematic representation of the simulated system. The structure is a thin film with a thickness $L_z$ much smaller than its lateral dimensions $L_x$ and $L_y$. The red area at $y=0$ is an interface layer with a width $\delta ;k_i,k_r$, and $k_t$ are the wave vectors of incident, reflected, and transmitted SW beams, respectively; the wave vectors of GH shift-free reference reflected and refracted beams are denoted as $k_{r,\mathrm{ref}}$ and $k_{t,\mathrm{ref}}$, respectively; ${\Delta }_t$ is the total lateral shift (along the interface) of the transmitted SW beam with respect to the incident beam.

V. N. Krivoruchko, A. S. Savchenko, and V. V. Kruglyak
Phys. Rev. B 98, 024427 (2018)

An external electric field can modify the strength of the spin-orbit interaction between spins of ions in magnetic crystals. This influence leads to a spin-wave frequency shift that is linear in both the applied electric field and the wave vector of the spin wave. Here we study theoretically the external electric field as a means of control of the spin-wave power flow in thin ferromagnets. The spin-wave group velocity and focusing patterns are obtained from the slowness (isofrequency) curves by evaluating their curvature at each point of the reciprocal space. We show that the combination of the magnetodipole interaction and the electric field can result in nonreciprocal unidirectional caustic beams of dipole-exchange spin waves. We demonstrate that the degree of asymmetry of the spin-wave power flow can be tuned with the external electric field. Our findings open a novel avenue for spin-wave manipulation and development of electrically tunable magnonic devices.

Fig.1. The group velocity overall patterns. Here each contour in the figure represents a slowness surfaces and each successive contour represents a frequency difference f = 0.2 GHz; the first isofrequency contour is at f = 7.8 GHz.  (left panel) E = +35 V/μm, and (right panel) E = −35 V/μm.