Ferromagnetic films with magnon bandgap periodic structures: Magnon crystals

A new type of photonic crystals is proposed. The new crystals have a forbidden gap in the microwave spectrum of magnetostatic spin waves, and, by analogy with photonic crystals, they are called magnon crystals. Specimens of such crystals were fabricated on the basis of yttrium iron garnet films. The surfaces of ferromagnetic films containing two-dimensional etched hole structures were studied by atomic force and magnetic force mag-netometry. The propagation of spin waves through the magnon crystals was investigated.     

Magnetostatic spin waves in two-dimensional periodic structures (magnetophoton crystals)

Series of experiments are carried out to study the propagation of magnetostatic spin waves in ferromagnetic films containing 2D periodic structures formed by etched apertures. For spin waves, such films are analogous to photon crystals (namely, magnetophoton or magnon crystals). The spectra of waves transmitted through the structure display features associated with a change in the spin homogeneity due to etching or radiation loss, as well as with Bragg reflection effect or the emergence of forbidden gaps in the spectrum of propagating waves.     

Self-localized nonlinear surface magnetic polaritons in a ferromagnetic medium

The properties of electromagnetic waves propagating in a semibounded, nonlinear, ferromagnetic medium are investigated. It is shown that under certain conditions the interaction between the spin and electromagnetic waves results in the localization of volume polaritons near the surface. Self-localization of surface polaritons due to the nonlinear properties of the medium occurs thereby. The nonlinear Schrödinger equation for nonlinear surface and volume polaritons is derived, and the conditions under which solitons of these waves exist are determined. The wave intensity required to observe the predicted effects is estimated.     

Perfect-absorber metamaterial based on flower-shaped structure

We theoretically and experimetally investigated the narrow-band peak of perfect absorber (PA), which was realized with a metal–dielectric–metal scheme based on a flower-shaped structure (FSS). The PA slabs were designed and fabricated to work in the GHz range of electromagnetic radiation. The absorption is due to the magnetic influence and therefore, the resonance frequency can be easily controlled without affecting the efficiency of the absorption peak by changing the dimensional parameters of the FSS. In addition, the FSS also results in polarization independence of electromagnetic waves, as expected due to its geometry.     

Formation and restructuring of domain patterns with Pab2 symmetry

Results from studying the formation and restructuring of 2d domain patterns with Pab2 symmetry are presented. A specific feature of these patterns is that they can formed and remain stable for long periods of time in a zero bias field, making it easier to use domain patterns in magneto-optical devices. A method for finding the region of domain pattern formation with Pab2 symmetry is tested. The turning of a domain pattern at a target angle under the effect of a series of magnetic pulses is detected.     

Spatiotemporal dynamics of magnetostatic and spin waves in a transversely confined ferrite waveguide

Spatiotemporal dynamics of the multimodal propagation of magnetostatic waves in a transversally confined ferrite waveguide and the parametric excitation of spin wave under conditions of three-magnon decay processes are experimentally investigated by the Brillouin spectroscopy.     

Dispersion curves of bulk acoustic waves in an elastic body with a two-dimensional periodic structure of circular holes

The dispersion curves of bulk acoustic waves in systems of circular holes made in an isotropic elastic material are calculated by the finite-element method for the cases of the square and hexagonal symmetries of the hole arrangement. The presence of total band gaps for acoustic waves is demonstrated, and the presence of inverse quasi-transverse first-order modes is revealed. For the hexagonally symmetric system of holes, total band gaps are found in the region of higher-order modes. For waves with a purely shear polarization, the imaginary part of the wave number in the first band gap is calculated.     

Self-Action Effects in the Propagation of Surface Magnetostatic Wave Pulses in a Magnonic Crystal–Dielectric–Metal Structure

Technical Physics - We have analyzed the self-action effects in the propagation of surface magnetostatic wave (SMSW) pulses in a 1D magnonic crystal–dielectric–metal structure in which...     

Spatial–frequency selection of magnetostatic waves in a two-dimensional magnonic crystal lattice

Features of the propagation of magnetostatic waves in a tangentially magnetized magnonic crystal structure based on iron–yttrium garnet with a two-dimensional array of grooves on the surface are studied. Numerical simulation is performed by the finite element method and the dispersion characteristics and the spatial distribution of fields of eigenmodes of surface magnetostatic waves propagating in this structure are calculated. The characteristics of waves in the magnonic crystal structure are experimentally studied by means of Brillouin scattering. It is shown that the formation of waveguide channels is possible when the frequency of the input signal is close to the frequency of the band gap of the structure.     

Tamm States in Bragg Heterostructures on Waveguide Slot Lines

Tamm surface states are experimentally studied and calculated for a Bragg heterostructure consisting of two groups of periodic fragments of waveguide slot transmission line with finite sizes. The Tamm surface states are not observed in a perfect Bragg heterostructure. The Tamm surface states emerge in the presence of an interface element at the interface of two Bragg structures when the characteristics of the element differ from the characteristics of both Bragg structures.