Magnetostatic Wave Propagation Research Articles

Pass bands formation in YIG film with periodic metal grating

Experimental results on the magnetostatic surface wave (MSSW) propagation in an yttrium-iron garnet film with a periodical array of metal stripes on the surface are presented. An effect of the pass bands formation in the MSSW transmission characteristics contrasting to the known Bragg stop bands inherent in a periodical structure is reported and discussed. Our findings provide one more way to affect the spin wave propagation and realize a control in magnonic devices.

Спиновые волны в одномерных магнонных кристаллах с двумя пространственными периодами

The propagation of surface and backward volume magnetostatic waves in a one-dimensional magnonic crystal in the form of a yttrium iron garnet film with two periodic lattices of grooves with different periods etched on its surface was experimentally studied. It is shown that the form of the frequency dependence of the transmission coefficient of magnetostatic waves in such crystal is not a simple superposition of similar dependences for two magnonic crystals with the same lattice periods.

Генерация ЭДС магнитостатическими волнами в структуре ЖИГ(111)-Pt в слабых полях подмагничивания

In a structure of an epitaxial film of yttrium iron garnet (YIG) with crystallographic orientation (111) 11.8 μm thick and a 5 nm thick platinum (Pt) film deposited on its surface, the effect of EMF generation in a platinum film during the propagation of magnetostatic waves (MSW) in the structure was studied at values of the tangential constant magnetic field H less than the saturation field H_s~65 Oe of the YIG film. The experiments were performed in a geometry where the field H was parallel to the crystallographic direction [1¯21] and to the MSW antennas, and the distances from the input antenna to the output antenna and to the Pt film were ~5 mm and ~0.5 mm, respectively. In the structure under consideration, at |H|<H_s, a stripe domain structure (SDS) was formed, which in fields |H|<H_1~5 – 7 Oe acquired a branching character in the near-surface layer. In the range of fields H_1<|H|<H_2≈40 Oe, MSW propagation was observed in the frequency band ∆F_1~ 300-550 MHz, which was accompanied by EMF generation due to the inverse spin Hall effect. In the interval H_2<|H|≤H_s, MSW propagation was observed in the frequency band ∆F_2≈ 750-1750 MHz, while the frequency interval in which the EMF signal was recorded turned out to be several times smaller due to the development of MSW parametric instability.

Thermoelastic state of a magnetized ferrite plate during the propagation of volume magnetostatic waves

Thermoelastic state of a magnetized ferrite plate during the propagation of volume magnetostatic waves

Resonant and nonlinear phenomena during the propagation of magnetostatic waves in multiferroid, semiconductor and metallized structures based on ferromagnetic films and magnonic crystals

Purpose of this work is to compile an overview of a new and fruitful scientific direction in magnonics, which grew out of the works of Ph.D., Professor Yuri Pavlovich Sharaevsky, and related to the study of resonant and nonlinear phenomena during the propagation of magnetostatic waves in ferromagnetic films, ferromagnetic films with periodic inhomogeneities (magnonic crystals), coupled (layered and lateral) ferromagnetic structures, as well as ferromagnetic structures with layers of a different physical nature (semiconductor, ferroelectric, piezoelectric, normal metal layers). Methods. Experimental and theoretical methods have been used to study spin-wave excitations in a wide class of structures with ferromagnetic layers. In particular, experimental radiophysical methods of microwave measurements and optical methods of Mandelstam-Brillouin spectroscopy. For the construction of theoretical models, the following methods are used: the method of coupled waves, the method of crosslinking magnetic permeability at the boundaries of layers, the method of transmission matrices, long-wave approximation. Results. The presented results are of general scientific importance for understanding the basic laws of the joint influence of coupling, periodicity and interactions of different physical nature (the influence on the magnetostatic wave of deformation in periodic structures with piezoelectric, electromagnetic wave in structures with ferroelectric, electric current in structures with semiconductor, spin current in structures with normal metal). In applied terms, the identified effects open up wide opportunities for creation of new devices of spin-wave electronics with the possibility of dynamic control of characteristics when changing the electric and magnetic fields, as well as the power of the input signal. Conclusions. The review of the most interesting results obtained by the authors together with Yuri Pavlovich and which are an ideological continuation of the foundations laid by him is given.

Исследование интерференции поверхностных магнитостатических волн с помощью обратного спинового эффекта Холла

The effect of EMF generation due to the inverse spin-Hall effect during the propagation of surface magnetostatic waves (SMSW) in the structure of yttrium iron garnet (YIG) - platinum based on a two-layer YIG film with different saturation magnetizations of the layers ((4πM_1>4πM_2 ) has been experimentally studied. It was shown that the magnitude of the EMF resonantly increases at the frequencies of hybridization of the MSSW with the exchange modes of the structure. At the same time, at the frequencies of the MSSW of the layer with a higher magnetization, oscillations of the EMF are observed, caused by its hybridization with the exchange modes of both the layer with 4πM_1 and the layer with lower magnetization, which indicates the influence of interlayer exchange on the efficiency of spin pumping in the structure under consideration.The influence of the interference of counterpropagating MSSWs on the generated EMF has been studied.It has been shown that the EMF value is sensitive to the phase difference between counterpropagating MSSWs and oscillates.In this case, the amplitude of the oscillations is determined by the ratio of the wavelength of the MSSW and the length of the platinum film.

Investigation of the interference of magnetostatic surface waves using the inverse spin Hall effect

The effect of EMF generation due to the inverse spin-Hall effect during the propagation of magnetostatic surface waves (MSSW) in the structure of yttrium iron garnet (YIG) --- platinum based on a two-layer YIG film with different saturation magnetizations of the layers ((4π M1>4π M2) has been experimentally studied. It was shown that the magnitude of the EMF resonantly increases at the frequencies of hybridization of the MSSW with the exchange modes of the structure. At the same time, at the frequencies of the MSSW of the layer with a higher magnetization, oscillations of the EMF are observed, caused by its hybridization with the exchange modes of both the layer with 4π M1 and the layer with lower magnetization, which indicates the influence of interlayer exchange on the efficiency of spin pumping in the structure under consideration. The influence of the interference of counterpropagating MSSWs on the generated EMF has been studied. It has been shown that the EMF value is sensitive to the phase difference between counterpropagating MSSWs and oscillates. In this case, the amplitude of the oscillations is determined by the ratio of the wavelength of the MSSW and the length of the platinum film. Keywords: magnetostatic waves, yttrium iron garnet, platinum, interference, inverse spin Hall effect.

Modeling of Electromagnetic, Thermal, and Mechanical Processes in Magnetic Media with Regard for the Moment Factors

We study specific features of the construction of thermomechanical models for ferromagnetic (ferritic) solids with regard for the moment force factors caused by the interaction with electromagnetic fields. In particular, we obtain the input relations of these models in the presence of external fields in the form of a combination of constant magnetic fields with variable electromagnetic fields. These relations can be used for the analysis of specific practically important problems of the thermomechanical behavior of solids under the conditions of ferromagnetic resonance, induction heating in the course of magnetization, and propagation of magnetostatic waves in these solids.

2D Surface Spin Waves in Dynamic Magnonic Crystals Created by a Surface Acoustic Wave in YIG Films

Some results of the study of 2D propagation of surface magnetostatic spin waves (SMSW) in dynamic magnonic crystals (DMC) created by a surface acoustic wave (SAW) in a structure with a yttrium-iron garnet (YIG) film are presented. Such studies are interesting from the practical point of view of creating real relatively complex devices on spin waves when they propagate in different directions, and not only in the 1D case. The methods of experimental research are presented, in particular, the features of the method of excitation of SAW in the structure that do not lead to the appearance of additional magnetic anisotropy in it, a method for measuring the angular dependencies of SMSW using mobile antenna–probes is presented. The angular dependences of the magnonic band gap frequencies are measured. It is established that the transmission bands with the transformation of the reflected SMSW into other types of magnetostatic waves (MSW) exist at any angle values, while the intervals in which there are no SMSW transformations during reflections occur in a certain narrower range of angles. The angles of the directions of the wave vectors and the Poynting vector of the reflected SMSW were also measured. A satisfactory agreement was obtained with the calculation performed using the method of isofrequency curves and the laws of inelastic scattering SMSW on SAW.

Spectrum evolution of magnetostatic waves excited through ultrafast laser-induced heating

We study experimentally the influence of the laser-induced temperature gradient on the parameters of propagating magnetostatic surface waves in thin film of the ferromagnetic metallic alloy Galfenol Fe0.81Ga0.19. The material has a pronounced magnetocrystalline anisotropy and exhibits the long-distance propagation of magnetostatic surface waves excited with femtosecond laser pulses. The excitation pulse heats up the sample locally, what leads to the spatial-temporal change of magnetization and anisotropy parameters of the film, and thus excites the magnetostatic surface waves. We show experimentally that the spectrum of the excited waves narrows as they propagate in such a gradient medium. By changing the orientation of external magnetic field with respect to anisotropy axes of the sample, we control whether the low- or high-frequency part of the spin waves spectrum is suppressed.

EMF Generation by Propagating Magnetostatic Surface Waves in Integrated Thin-Film Pt/YIG Structure

Magnetostatic surface waves (MSSW) propagation and electromotive force (EMF) generation effects in 14.6 µm-thick yttrium iron garnet (YIG) film covered by 8 nm-thick Pt layer was studied. It was found that MSSW dispersion k = k(f) and transmission S21(f) characteristics in the YIG/Pt structure are very similar to that of the free YIG film. For YIG/Pt structure, we show that EMF (U) demonstrates non-monotonous frequency dependence U(f) and is characterized by two peaks U1,2. The first one (U1) is located near the short-wavelength (k → ∞) cut-off frequency of the MSSW spectrum and can be attributed to MSSW drag of electrons in YIG/Pt structure. The second one (U2) is located near the long-wavelength (k → 0) cut-off frequency of the MSSW spectrum and can be attributed to the inverse spin Hall effect due to the spin pumping.

Surface spin waves propagation in tapered magnetic stripe

We analytically investigate properties of magnetostatic surface spin wave propagation in irregular narrow ferromagnetic waveguides that are important elements of magnonic logic. The developed mathematical model is based on the Galerkin method. Theoretical investigations are proved by Brillouin light scattering spectroscopy. We demonstrate that the confinement effect in the narrow waveguide leads to multimode regime propagation, wave beats, and energy redistribution. These processes can be controlled by tuning the structure and excitation parameters. A gradual change in the waveguide width can be used to vary the spin wave energy density. Our results show that the impact of the width effect and the irregularity of the waveguide on the spin wave propagation are crucial.

Three-Dimensional Magnetostatic Waves Caused by Electromagnetic Fields in Metallized Ferrite Plates

By using a well-known technique for finding the characteristics of magnetic fields based on the method of decomposition of unknown quantities in a series in small parameter (chosen as the ratio of amplitude of the tangential harmonic field to the amplitude of normal constant field) and restricting ourselves to the first two terms of decomposition, we establish the conditions of excitation and study the regularities of propagation of three-dimensional magnetostatic waves in metallized normally magnetized ferrite plates depending on the character of the external electromagnetic field and electrophysical characteristics of the material.

Controlling the Properties of Spin–Wave Transport in a Semiring Magnon Microwavevguide

Spin-wave transport along a waveguide structure with disturbed translational symmetry has been investigated. A semiring portion of a magnon microwaveguide has been made of a YIG film. It has been shown that one can control the dynamic magnetization spatial distribution by varying the magnetic biasing angle in the microwaveguide plane. Under such conditions, the transmission coefficient of standing waves changes noticeably. The structure suggested in this paper allows the rotation of spin-wave signals in an irregular configuration under the conditions of surface magnetostatic wave propagation. This effect may be used in planar magnon networks.

Generation of Dark Multisoliton Complexes in a Magnonic Ring Resonator with Dispersion Management and Competing Nonlinear Spin-Wave Interactions

Multisoliton complexes have been generated in an active ring resonator with an L-shaped magnonic microwaveguide and a saturated amplifier. It has been shown that an irregular microwaveguide simultaneously supports both the propagation of magnetostatic spin waves with different (normal and anomalous) dispersion and competition between three- and four-wave spin-wave interactions. Generated multisoliton complexes consist of quasiperiodic sequences of two dark parametric pulses containing “soliton trains” consisting of three dark ultrashort four-wave envelope solitons. It has been found that quasiperiodic sequences of multisoliton complexes generated by the active ring resonator with a regular magnonic microwaveguide consist of one dark parametric pulse, which also contains three dark four-wave solitons. However, in contrast to the preceding case, four-wave solitons, having a longer duration, do not form soliton trains inside a dark parametric pulse.

Управление свойствами спин-волнового транспорта в полукольцевом магнонном микроволноводе

AbstractSpin-wave transport along a waveguide structure with disturbed translational symmetry has been investigated. A semiring portion of a magnon microwaveguide has been made of a YIG film. It has been shown that one can control the dynamic magnetization spatial distribution by varying the magnetic biasing angle in the microwaveguide plane. Under such conditions, the transmission coefficient of standing waves changes noticeably. The structure suggested in this paper allows the rotation of spin-wave signals in an irregular configuration under the conditions of surface magnetostatic wave propagation. This effect may be used in planar magnon networks.

Spin Waves in Magnetic Films with Antidots

This review presents the data of the experimental investigation of the propagation and decay of magnetostatic spin waves (MSWs) obtained when analyzing the Brillouin light scattering data in yttrium iron garnet films. It is shown that the effect of nonreflected wave connected with artificial antidots in films leads to a significant increase in the intensity and propagation length of the magnetostatic spin waves in yttrium iron garnet.

Features of Dispersion Characteristics of Surface Spin Waves in Coupled Antiferromagnetic Films with Easy-Axis Anisotropy

Propagation of magnetostatic spin waves in a layered structure consisting of two vertically coupled via a nonmagnetic dielectric layer antiferromagnetic (AFM) films has been studied. The results of calculation of the dispersion dependence for the AFM films with an easy-axis anisotropy are presented. It has been shown that splitting of coupled modes occurs in the region of AFM resonance frequencies. The behavior of coupled modes as a function of the parameter of coupling between films has been studied.

Volume Magnetostatic Spin Waves in 3D Ferromagnetic Structures

Propagation of volume spin magnetostatic waves in meander-shaped ferromagnetic films with vertically and horizontally coupled segments is studied. Conditions under which forward and backward volume magnetostatic waves simultaneously exist in the films are determined. Micromagnetic simulation and expansion in terms of plane waves are used to calculate internal effective magnetic fields and dispersion characteristics of the waves in such structures. Spectra of coupled waves in meander-shaped vertically coupled ferromagnetic films are studied. Prospects for application of the above structures in the development of magnonic elements are analyzed.

Fresnel diffraction of spin waves

The propagation of magnetostatic forward volume waves excited by a constricted coplanar waveguide is studied via inductive spectroscopy techniques. A series of devices consisting of pairs of sub-micrometer size antennae is used to perform a discrete mapping of the spin wave amplitude in the plane of a 30-nm thin YIG film. We found that the spin wave propagation remains well focused in a beam shape of width comparable to the constriction length and that the amplitude within the constriction displays oscillations, two features which are explained in terms of near-field Fresnel diffraction theory.