When an electric current flows through the NiFe/IrMn structure, a significant redistribution of the intensities of the direct Stokes and inverse anti-Stokes lines in spectra of Brillouin scattering on thermal spin waves is observed. This is due to a change in the orientation of uniaxial anisotropy and the corresponding easy axis of the exchange shift under the action of the spin–orbit torque in the IrMn antiferromagnet, which in turn affects the dynamics of spin waves in the neighboring ferromagnetic NiFe layer. The detected effect indicates that spin-wave processes in a ferromagnet can be controlled by applying a spin current to change the magnetic anisotropy of the NiFe/IrMn interface.

Here we report recent data on the phenomenon of total nonreflection of spin waves (NRSWs). Using space- and phase-resolved Brillouin light scattering we experimentally studied the amplitude, direction, and phase of the NRSW in yttrium iron garnet films with artificial defects---an antidot array. An NRSW in the form of a focused beam of high intensity with the group velocity pointing along the line of defects is observed only for a critical angle between spin-wave phase velocity and an antidot array direction in a magnetic field. It is shown that the NRSW is an independent noncollinear spin wave arising as a result of the anisotropic nature of the propagation of surface magnetostatic spin waves in a magnetic medium. The numerical simulations agree well with experimental data. Micromagnetic simulations performed let us elucidate the phenomenon of the NRSW and map the spin-wave profile of dynamic magnetization inside the NRSW. The estimated mean free path of the NRSW reaches about 1 mm in the yttrium iron garnet film with a thickness of a few micrometers. These results demonstrate a unique approach to focusing and enhancing spin waves in magnetics through the use of artificial defects.

In this work, we present the results of investigations performed on hematite (α-Fe2O3), which is an antiferromagnet with weak ferromagnetism. Through the use of Brillouin light scattering spectroscopy, we studied experimentally the excitation of quasi-ferro- and antiferromagnetic modes in the bulk hematite. We investigated the influence of relative mechanical strains, ϵyy, on the frequencies of quasi-ferro- and antiferromagnetic modes. Also, we considered the angular dependence of the frequency of the quasi-ferromagnetic mode on the external magnetic field. Our results indicate that hematite is a suitable material for strain-controlled magnonic devices.

Purpose. Investigation of the joint manifestation of the effects of anisotropic signal propagation, coupling, and nonlinear power dependence of the medium parameters in a lattice of laterally and vertically coupled spin-wave (SW) microwaveguides. Consideration of the case of the influence of the rotation of the magnetization angle and the change of the lateral gap between microwaveguides located on the same substrate on the transverse profile of the spin-wave beam and the spatial localization of the SW amplitude. Methods. The method of micromagnetic modeling based on the numerical solution of the Landau–Lifshitz–Hilbert equation shows the possibility of controlling the direction of propagation of SW in an ensemble of laterally and vertically coupled iron yttrium garnet (YIG) microwaveguides by changing the magnetization angle. By the method of numerical integration of the system of coupled discrete nonlinear Schrodinger equations, the possibility of changing the transverse profile of the spin-wave beam by changing the level of the initial signal amplitude is shown. Results. The spatial distributions of the components of the dynamic magnetization of the SW excited in two microwaveguides located on the same substrate obtained in micromagnetic simulations indicate a change in the character of localization of the SW power in the output sections of the microwaveguides. At variation of the lattice magnetization angle, a shift of the threshold power value is observed, at which a characteristic curbing of the transverse width of the spin-wave beam in the nonlinear mode appears. Conclusion. When excitation of surface magnetostatic SW in a lattice of laterally and vertically coupled microwaveguides, a transformation of the transverse profile of the wave is observed at a deviation of the magnetization angle of the structure by 15º , which is manifested in the change of the SW length and its localization in each of the microwaveguides. The combined effects of dipole coupling, gyrotropy, and nonlinearity of the medium make it possible to control the value of the threshold power of the SW, at which the mode of diffractionless propagation of the spin-wave beam is realized in a single layer of the structure.

Here we present the results of the study of the joint manifestation of the effects of anisotropic spin waves (SW) propagation in a system of laterally and vertically coupled ferrimagnetic microwaveguides when both the magnetization angle and air gap between waveguide are changed. The micromagnetic modeling method based on the numerical solution of the Landau–Lifshitz–Hilbert equation was used to provide the possibility of controlling the direction of SW propagation in a system of laterally and vertically coupled iron-yttrium garnet (YIG) microwaveguides by changing the magnetization angle and direction of the equilibrium of magnetization direction. The spatial distributions of the dynamic magnetization out-of-plane component of the SW excited in two microwaveguides located on the same substrate obtained in micromagnetic simulations indicate a change in the nature of the SW power localization in the output sections of the microwaveguides. The variation of the magnetization angle of the array leads to the variation of the transverse width of the spin-wave beam and localization of the amplitude maximum in each of the microwaveguides within the array. The joint manifestation of dipole coupling effects in each separately taken layer of the structure realizes the regime of non-diffraction propagation of the spin-wave beam.

A magnon-assisted electrically driven ``mirror'' with tuned frequency of the reflected light is created. The effect of in-plane electric current on asymmetry of Stokes--anti-Stokes Brillouin intensities in NiFe/IrMn exchange-biased patterned structures is found. Electric current directed along external magnetic field suppresses anti-Stokes component in Brillouin light-scattering spectra, while the opposite direction of current results in suppression of the Stokes component. We show that spin currents arising in the IrMn layer induce spin-orbit torque affecting uncompensated antiferromagnetic moments at the interface, rotate the antiferromagnetic moments, change bias field, and finally determine direction of dominating spin-wave propagation. The possibility of electric control of spin-wave direction and manipulation over Stokes and anti-Stokes intensities opens a way for design of electro-optical devices switching light frequency.

Numerical micromagnetic modeling is used to analyze regimes of the propagation of spin waves in arrays of microwaveguides whose configuration corresponds to the excitation of two central channels of a surface layer or backward volume-type magnetostatic spin waves. It is shown that the proposed structure selects the spatial frequency of a signal with an efficiency that depends on the mutual orientation of the bias magnetic field and the direction of wave propagation.

Методом численного моделирования показана возможность управления направлением распространения спиновых волн в ансамбле латерально и вертикально связанных микрополосок железо-иттриевого граната (ЖИГ). С помощью метода конечных элементов проведен расчет величины длины связи спиновых волн в латеральной и вертикальной геометриях. Численное значение коэффициентов связи спиновых волн находилось методом конечных элементов в результате решения системы уравнений Максвелла с тензором магнитной проницаемости полученным из линеаризации уравнения Ландау--Лифшица. Методом интегрирования уравнения связанных волн показана возможность изменения направления распространения спин-волнового сигнала в рассматриваемой структуре. Полученные в микромагнитном моделировании спектры прохождения сигнала свидетельствуют об изменении характера локализации мощности спиновой волны в выходных секциях микроволновода при изменении частоты на входе структуры. Система латерально и вертикально связанных микроволноводов представляет собой элемент межсоединений для трехмерных топологий магнонных сетей, демонстрируя при этом функциональные возможности пространственно-частотного демультиплексирования сигнала. Ключевые слова: спиновые волны, магноника, латеральные структуры, магнонный кристалл, ансамбли связанных структур.

The possibility of controlling the direction of propagation of spin waves in an ensemble of laterally and vertically connected microstrips of iron-yttrium garnet (YIG) is shown by numerical modeling. Using the finite element method, the magnitude of the coupling length of spin waves in lateral and vertical geometries was calculated. The numerical value of the spin wave coupling coefficients was found by the finite element method as a result of solving a system of Maxwell equations with a magnetic permeability tensor obtained from the linearization of the Landau-Lifshitz equation. By integrating the equation of coupled waves, the possibility of changing the direction of propagation of the spin-wave signal in the structure under consideration is shown. The signal transmission spectra obtained in micromagnetic modeling indicate a change in the nature of the localization of the spin wave power in the output sections of the microwave with a change in the frequency at the input of the structure. The system of laterally and vertically connected microwave diodes is an element of interconnections for three-dimensional topologies of magnon networks, while demonstrating the functionality of spatial-frequency signal demultiplexing. Keywords: spin waves, magnonics, lateral structures, magnonic crystal, ensembles of related structures. Keywords: spin waves, magnonics, lateral structures, magnonic crystal, ensembles of related structures.

Diffraction of a backward volume spin wave on a through hole in a ferrite plate is investigated experimentally and theoretically for when the length of the spin wave is greater than the diameter of the hole and the linear transducer exciting the wave is perpendicular to an external uniform magnetic field. It is found that in one direction of the possible super-directional propagation of the wave, a distinct shadow of the hole is observed at a considerable distance from the latter. Good agreement between the experimental and theoretical results is obtained.

The features of spin-wave transport in a system of coupled magnetic microwaveguides with perpendicular magnetization relative to the longitudinal axis of the system are considered. In this case, the system has uniaxial anisotropy, the horizontal and vertical coupling coefficients have different signs, and the isofrequency surfaces have a "saddle" shape. In the propagation of transversely limited beams of spin waves, the type of curvature of the wave fronts is determined by the direction of wave propagation relative to the external magnetic field. Keywords: spin waves, magnonics, microwaveguides, lateral structures.

The purpose of research is to study of characteristics of the Fano resonance in a coupled system of nonlinear microwave-guides and resonators depending on geometric parameters of the systems, magnitude of the coupling between them, and the intensity of spin waves. Methods. Linear and nonlinear spin-wave excitations in lateral systems of irregular microwave-guides and resonators based on films of yttrium iron garnet are considered. Using micromagnetic simulation of spin-wave excitations and numerical integration of the coupled wave equation system, the transfer characteristics of the "microwave-guide - resonator" system and the Fano resonance parameters are calculated taking into account the cubic nonlinearity of magnetic media. Results. Based on the numerical integration of the system of equations of coupled waves that take into account the cubic nonlinearity of the magnetic media, theoretical studies have been carried out of the dependences of the transfer and phase characteristics of the "microwave-guide - resonator" system on the intensity of surface spin waves. Features of the demonstration of constructive and destructive interference of spin waves at Fano resonance are studied. Dependences of characteristics of the parameters of the Fano nonlinear resonance (asymmetry coefficient, resonance frequency shifts) on the intensity of spin-wave excitations are established. Conclusion. Results can be used to create spin-wave demultiplexers, power dividers and microwave couplers based on the lateral system of magnetic waveguides as a threshold element for neuromorphic networks, etc.

The features of spin-wave transport in a system of coupled magnetic microwaveguides with perpendicular magnetization relative to the longitudinal axis of the system are considered. In this case, the system has uniaxial anisotropy, the horizontal and vertical coupling coefficients have different signs, and the isofrequency surfaces have a "saddle" shape. In the propagation of transversely limited beams of spin waves, the type of curvature of the wave fronts is determined by the direction of wave propagation relative to the external magnetic field.

Results are presented from experiments and calculations to study the Bragg diffraction of a beam of surface spin waves with low diffraction divergence on a low-contrast magnon crystal in which the lattice vector is parallel to the external magnetic field. The beam is displaced as it passes through the magnon crystal. The beams of the zero and first orders of diffraction are broadened and narrow superdirectional duplicates of these beams appear.