S. A. Nikitov

Kotel'nikov Institute of Radioengineering and Electronics, Russian Academy of Sciences · Department of Spintronics

The main features of the nonlinear pulse propagated in iron-yttrium-garnet magnonic crystal with thickness 100 nm and a periodic system of grooves on the surface are studied. We have demonstrated the possibility of the formation of gap solitons at a frequency inside the band gap of the magnonic crystal when the input signal power is increased. A fu...

Energy transfer is investigated in coupled planar magnon "ferromagnet-normal metal" heterostructures with equivalent amplification and damping of spin waves, in which an exceptional point (point in the space of the parameters of a system where its eigenvalues and eigenvectors degenerate) can be observed. It is shown that an increase in the direct c...

The paper presents the theoretical results that demonstrate the bright envelope soliton formation on a backward electromagnetic wave existing in a double negative medium based on a transversely magnetized thin film of ferromagnetic semiconductor (FM SC). An analytical model of a magnetized ferromagnet containing magnetized cold and collisionless el...

The paper presents the experimental results that demonstrate the formation of spatiotemporal parametric patterns in active ring resonators based on one-dimensional single- and bicomponent magnonic quasicrystals (MQCs). Such patterns are formed through the nonlinear parametric three-wave decay of a magnetostatic surface spin wave (MSSW). It is shown...

Spin pumping from canted antiferromagnets is a cutting-edge topic in modern spintronics. The interest for fundamental and applied research that these materials arouse is related to their unusual structure, namely, with a small canting of the magnetic sublattices, which is explained by the presence of the Dzyaloshinskii–Moriya interaction. Through t...

The temperature dependences of the heat capacity were measured and the general patterns of the formation of the phonon spectrum of single crystals of solid solutions of yttrium-lutetium aluminum garnets Y3–xLuxAl5O12 at 0 x 3 were studied in the temperature range from 1.9 to 220 K. Based on the data obtained below 10 K, the Debye temperatures were...

We propose the design of single-layer, double-layer, and triple-layer configurations of magnonic ring couplers, which perform spin-wave mode filtering and provide interlayer signal transmission in three-dimensional architectures of magnonic integrated circuits. We study the characteristics of spin-wave dynamics in coupled magnonic structures with a...

Here we present the nonreciprocal propagation of caustic beams and channeling of the backward volume spin wave in an yttrium-iron-garnet structure with the longitudinal symmetry axis and broken translational symmetry. The experimental method of Brillouin spectroscopy and the numerical micromagnetic methods are used to study the mechanisms of contro...

The temperature dependences of the heat capacity were measured and the general patterns of the formation of the phonon spectrum of single crystals of solid solutions of yttrium-lutetium aluminum garnets Y 3 – x Lu x Al 5 O 12 at 0 ≤ x ≤ 3 were investigated in the temperature range from 1.9 to 220 K. According to the data obtained at temperatures be...

International conference Meta-Optics for Science and Technology, Samarkand, Uzbekistan 8-11.10.2024. most2024.com

Canted antiferromagnets offer great potential in fundamental research and for use in applications due to their unique properties. The presence of the Dzyaloshinskii–Moriya interaction (DMI) leads to the existence of a weak ferromagnetic moment at room temperature. We study both theoretically and experimentally microwave spin pumping by a quasi-ferr...

Microwave spin pumping from ferromagnetic lutetium iron garnet (Lu 3 Fe 5 O 12 ) has been theoretically and experimentally investigated. The magnetization vector precession excited by a microwave magnetic field is transformed into a dc voltage due to the inverse spin Hall effect in the lutetium iron garnet/heavy metal heterostructure (Lu 3 Fe 5 O 1...

The research experimentally demonstrates the direct electric current control of hyperchaotic packets of dissipative dark envelope solitons that are self-generated in a microwave active ring resonator containing two nonlinear elements: a one-dimensional magnonic crystal (MC) with dynamic line defect and a transistor amplifier. The hyperchaotic packe...

This paper explores the nonlinear dynamics of mutually coupled spin-torque nano-oscillators and examines the relationship between non-isochronism and the appearance of exceptional points (EPs). We demonstrate that by manipulating the amplitudes of the driving force and the angles of the external bias magnetic field and spin-polarized current, it is...

In this work, we present the results of a systematic experimental study of linear and parametric spin wave resonant excitation accompanied by spin currents (spin pumping) in a multifrequency composite bulk acoustic wave resonator with a ZnO-YIG-GGG-YIG/Pt structure. The features of magnetic dynamics excitation in YIG films due to magnetoelastic cou...

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...

The influence of double (electrical and magnetic) nonlinearity on the Bragg resonances of the hybrid electromagnetic-spin waves in a multiferroic crystal has been theoretically and experimentally revealed. The multiferroic crystal consists of an yttrium iron garnet layer with a periodic system of grooves on the surface and a ferroelectric strontium...

The magnetic properties of the surface layer of an epitaxial bismuth-doped iron garnet film with a weak uniaxial anisotropy are studied by magnetic force, optical, and nonlinear optical microscopy. A significant modulation of optical second harmonic generation intensity along stripe domains is detected near the free film surface. This modulation is...

Specific features of Bragg resonances in a magnonic crystal with a metallic grating on the surface with two periods have been revealed. A theoretical model describing the spectral characteristics of magnetostatic waves has been constructed by matching the permeabilities of the metal layer and the ferromagnetic film at the interface between them and...

Left-handed (LH) metamaterials are generally structured materials possessing abnormal electromagnetic properties due to both negative permittivity and permeability. One of these properties is a backward wave (BW) propagation, in which the phase and group velocities are opposite to each other. Here we investigate the electrodynamic (dispersion and e...

The principle of operation of a spin waves phase comparator, made on the basis of ferromagnetic film, is described. Mathematical model of equivalent electrical scheme is investigated. The dependence of the output voltage on the comparator on the phase difference of the input microwave signals is obtained. Micromagnetic modelling of conversion of sp...

This paper presents a model that explains the influence of external pressure on the resonant frequency of a bulk crystal a–Fe2O3 in an external magnetic field. The dynamics of vectors l and m before and after the Morin temperature TM are considered. The dependences of the resonant frequency on pressure and external magnetic field for the cases H║(H...

The theory of the nonlinear dynamics of a canted antiferromagnet-based (AFM) spin-Hall oscillator with weak ferromagnetism caused by the strong Dzyaloshinskii–Moriya interaction between magnetic sublattices is rigorously studied. The AFM oscillator’s frequency tuning is carried out both due to a DC spin-polarized current flowing through the normal...

We theoretically study the linear and nonlinear dynamics of a system of mutually coupled magnetic vortices. We consider the excitation of vortex dynamics by both an external harmonic magnetic field and a spin-polarized current. The results based on the Thiele equations for the motion of coupled vortices are compared with the numerical integrations....

Осуществлена индуцированная светом генерация темных диссипативных солитонов огибающей в микроволновом активном кольцевом резонаторе, содержащем нелинейный бикомпонентный магнонный кристалл. Последний представляет собой пленку железо-иттриевого граната, на поверхности которой располагается одномерная периодическая структура из тонких полупроводников...

The paper reports on laser-induced Bragg resonances in the spectrum of magnetostatic waves in a heterostructure based on a ferrite film [yttrium iron garnet (YIG)] with periodic strips of semiconductor material (Si) on the surface. Laser irradiation of such a structure leads to the formation of Bragg bandgaps due to the modulation of the Si conduct...

This paper reports on the hysteresis and frequency tuning (electrical and magnetic) of the Bragg resonance in the spectrum of spin waves in a multiferroic structure based on YIG (100 nm thick) and HZO (10 nm thick) with a periodic modulation of parameters. The resonance can be tuned in a wide frequency range of 1–4 GHz by a magnetic field H and in...

The report presents the history of the creation and development of the Kotelnikov Institute of Radioengineering and Electronics of Russian Academy of Sciences, the main scientific directions and achievements, development prospects are outlined.

Based on the results of processing an interferometric pair of radar images with synthesized aperture (SAR) L-band PALSAR-2 taken over the territory of the Bureya landslide in May 2019 and May 2020 from the ALOS-2 satellite, a new unstable surface area was discovered. Rated the average monthly rate of soil displacement is up to 1 cm/month along the...

The influence of nonlinearity on the displacement of a singular point in a system of two connected Duffing oscillators when coupling coefficients and insertion losses change. It is shown that the displacement of the singular point when the nonlinearity coefficient changes is accompanied by a decrease in the amplitude of the excited oscillations and...

Based on the results of processing an interferometric pair of PALSAR-2 L-band synthetic aperture radar (SAR) images taken over the territory of the Bureya landslide in May 2019 and May 2020 from the ALOS-2 satellite, a new unstable surface region has been discovered. The average monthly rate of soil displacement was estimated to be up to 1 cm/month...

The spectral properties of gap electroacoustic waves in a PT -symmetric structure of piezoelectrics of symmetry class 6mm separated by a gap are theoretically investigated. The spectra were calculated for lead germanate (non-zero transverse piezoactivity) and barium titanate (symmetry class 4mm - zero transverse piezoactivity). It has been establis...

We report on the coupling of spin waves propagating as guided modes of yttrium iron garnet stripes. Three stripes are placed parallel to each other and separated by gaps that are small enough to provide nearest-neighbor coupling. We term this geometry "bilateral stripes." The origin of the coupling is the long-ranging dynamic, stray (dipole) field...

A method for studying solid dielectrics under conditions of nonstationary propagation of subterahertz phonons is presented. The method analyzes the transport characteristics of thermal phonons in the helium (He) temperature range (2–4 K) in diffusion mode and makes it possible to investigate the following: the kinetic characteristics of thermal pho...

Эпитаксиальная гетероструктура на основе манганитных пленок стронция и лантана-стронция (SrMnO3 и La0.7 Sr0.3 MnO3 ) изучалась в данной работе. Измерены спектры ферромагнитного резонанса, угловые зависимости резонансного поля при различных температурах, плоскостная и кубическая анизотропия, а также температурные зависимости намагниченности. Получен...

In this work we present a model explaining the properties of magnetoelastic waves propagation in the heterostructure containing an antiferromagnetic layer on a non-magnetic elastic substate. Horizontally polarized shear surface waves (SH-waves) propagating in thin film are Love waves. The dispersion characteristic of magnetoelastic waves in such st...

The method of moments is developed and employed to analyze the equilibrium correlation functions of the magnetization of ferromagnetic nanoparticles in the case of inertial magnetization dynamics. The method is based on the Taylor series expansion of the correlation functions and the estimation of the expansion coefficients. This method significant...

The review covers current achievements and prospects for the development of fiber sensorics associated with tilted fiber Bragg gratings (TFBGs), including metal-coated (plasmonic) sensors. The physical nature of the excitation of the cladding modes in such structures is discussed, and the main properties of TFBGs are considered. Special attention i...

We demonstrate the laser-induced control over spin-wave (SW) transport in the magnonic crystal (MC) waveguide formed from the semiconductor slab placed on the ferrite film. We considered bilayer MC with periodical grooves performed on the top of the n-type gallium arsenide slab side that oriented to the yttrium iron garnet film. To observe the appe...

We report on the spin-wave propagation along a magnonic waveguide with a local area of decreased magnetization, which is induced by heating produced with a focused laser spot. A phase-sensitive Brillouin light scattering technique is used to image how the spin wave propagates along the waveguide with a local heat landscape. Frequency-selective sign...

Dynamic control of chaotic dark dissipative envelope solitons in a microwave active ring resona-tor containing two nonlinear elements: a one-dimensional magnonic crystal (MC) with a dynamic linear defect and a transistor amplifier is performed. Dissipative envelope solitons are formed on a long-wavelength surface magnetostatic wave propagating in t...

The results of studying the influence of the thickness of La0.7Sr0.3MnO3 films obtained by magnetron sputtering on (110) NdGaO3 substrates on the magnetic and crystallographic properties using ferromagnetic resonance and X-ray spectroscopy are presented. The dependences of the uniaxial and cubic anisotropy fields on the sample thickness are establi...

In this work we present a model explaining the properties of magnetoelastic waves propagation in the heterostructure containing an antiferromagnetic layer on a non-magnetic elastic substate. The dispersion characteristic of magnetoelastic waves in such structure was obtained, and the effect of variation of the thickness of the antiferromagnetic lay...

The present work is devoted to the study of the optically induced formation of the band structure of a magnon crystal consisting of a ferrite microwave diode loaded with a semiconductor with periodic thickness modulation. Using the Brillouin light scattering method, it is demonstrated that an increase in the power of laser radiation illuminating th...

Dynamic control of chaotic dark dissipative envelope solitons in a microwave active ring resona tor containing two nonlinear elements: a one-dimensional magnonic crystal (MC) with a dynamic linear defect and a transistor amplifier is performed. Dissipative envelope solitons are formed on a long-wavelength surface magnetostatic wave propagating in t...

We present a model of a sub-THz frequency spectrum analyzer based on the antiferromagnet/non–magnetic metal heterostructure. The considered structure operates in the active self–oscillation regime with the high Q–factor (closed to $10^{6}$ ) and is phase–locked to the analyzed signal, while the frequency of the oscillator is linearly tuned by the...

Introduction. Recent studies into the properties of spintronic oscillators have led to broadening their scope of practical application as devices for generating and processing signals. The practical implementation of spintronic oscillators is, however, significantly limited by their low power capacity, thus requiring synchronization between devices...

The method of moments is developed and employed to analyze the equilibrium correlation functions of the magnetization of ferromagnetic nanoparticles in the case of inertial magnetization dynamics. The method is based on the Taylor series expansion of the correlation functions and the estimation of the expansion coefficients. This method significant...

A concept of a subterahertz (sub-THz) frequency range signals detector based on a ferrimagnet/normal metal (FiM/NM) heterostructure is proposed. An external linearly polarized electromagnetic (EM) wave excites precession in the FiM and spin pumping at the FiM/NM interface. The excited spin current in the NM converts into a direct current via the in...

Antiferromagnetic (AFM) materials possess a well-recognized potential for ultrafast data processing thanks to their intrinsic ultrafast spin dynamics, absence of stray fields, and large spin transport effects. The very same properties, however, make their manipulation difficult, requiring frequencies in THz range and magnetic fields of tens of Tesl...

Purpose of this paper is the development and creation of the magnetic metasurfaces with metallic inclusions operating both in the microwave and terahertz frequency ranges. Methods. The Maxwell’s equations and the expressions for the effective medium parameters are used to build the analytical models of the magnetic metasurfaces based on either a fe...

Studying the spin-wave (SW) propagation in 3D periodic structures opens new possibilities for joining functional units placed on the different layers of the magnonic circuitry. In the path toward 3D magnonics, the main challenge is the fabrication of large-scale 3D magnetic structures with nanometric precision control of geometry and material compo...

Spontaneous symmetry breaking is a source of the phase transition in a variety of physical systems including such as non-Hermitian. It has recently been demonstrated that so-called exceptional points, which are singularities in non-Hermitian systems, separate the areas with symmetrical and asymmetrical eigenstates. Such separation is evidence of ph...

The main features of the nonlinear spin wave propagating in the magnonic crystal/semiconductor layered heterostructure are studied. We demonstrate the possibility of double electric and magnetic control of the gap solitons parameters (their number, threshold of formation, velocity), bistability of spin waves, switching powers and nonlinear band gap...

We introduce a theoretical model presenting a PT-symmetric system of two planar coupled magnonic ferromagnetic (FM) waveguides covered by thin layers of nonmagnetic metal with a strong spin-orbit interaction [heavy metal (HM)]. The eigenvalues in PT-symmetric systems change from real to complex at exceptional points. In magnonics, PT symmetry is ac...

A method of nondestructive control of the layered structure of submicron ferrite films comparable to the thickness of the transition (diffusion) layer at the film-substrate interface was proposed. The control technique was based on measurements of spin-wave resonance frequencies and mathematical processing of the measurement results. It was found t...