The purpose of this work is to experimentally study, using the inverse spin Hall effect (ISHE), the detection of focused beams of magnetostatic surface waves (MSSW) in integrated YIG (3.9 µm) / Pt (4 nm) thin-film microstructures, where the focusing effect was ensured by the curvilinear shape of the exciting antenna. Make a comparison with the case of detecting MSSWs excited by a rectilinear antenna. Methods. Experiments were carried out using the delay line structures based on the YIG/Pt. The amplitude-frequency characteristics of the YIG/Pt structure and the frequency dependence of the EMF (V(f)) induced in platinum were studied. Results. It was shown that at frequencies f near the long-wavelength limit of the MSSW spectrum, the magnitude of the EMF V(f) generated by a focused MSSW can be several times higher than the values of V(f) in the case of MSSW excitation by a common (straight) antenna. In this case, in the short-wavelength part of the spectrum, on the contrary, the magnitude of the EMF generated by the focused MSSW beam turns out to be noticeably smaller. This behavior is associated with chromatic aberration of the focusing antenna for the MSSW, which manifests itself in the frequency dependence of the focal length of the antenna, which is confirmed by the results of micromagnetic modeling. It is shown that the drop in the EMF signal generated by a focused MSSW beam in the short-wavelength part of the spectrum is associated with the focus reaching the area of the YIG not covered with the Pt film. In this case, the increase in V(f) in the long-wavelength region of the MSSW spectrum is explained by an increase in the linear power density of the MSSW and the formation of caustics under the Pt film. Conclusion. Obtained results can be used for the development of highly sensitive spin wave detectors and the creation of spin logic devices.

Spin pumping by surface and backward volume magnetostatic waves in YIG/Pt structures is experimentally studied and analyzed. It is shown that at frequencies corresponding to van Hove singularities in the density of states of the spin wave spectrum, an increase in the efficiency of electron-magnon scattering and spin current generation takes place. The obtained results are important for spin wave-based spintronic devices development.

Using the inverse spin hall effect, a study of spin pumping by running magnetostatic surface waves in YIG/Pt microstructures was carried out, where an Fe application was used as a source of a local non-uniform magnetic field. The results of measuring the frequency dependences of the EMF are presented. It is shown, that the Fe application leads to an upward shift in frequency and «bluring» of the EMF peak near the lo-frequency boundary of the magnetostatic surface waves – its width increases, the amplitude decreases compared to the case of the YIG/Pt structure without the application.

Spin pumping by traveling magnetostatic surface waves (MSSW) has been experimentally investigated in YIG|Pt structures made on the basis of 0.9, 4, 8, 14 and 18 µm thick YIG epitaxial films. It is found that at frequencies corresponding to the van Hove singularities in the density of states of the MSSW spectrum of the structure, the EMF value generated due to the inverse spin Hall effect increases. This increase is associated with an increase in the spin mixing conductance of the YIG|Pt interface due to an increase in the efficiency of electron-magnon scattering at the frequencies of van Hove singularities in the spin wave spectrum.

Spin pumping by traveling magnetostatic surface waves (MSSW) has been experimentally investigated in YIG|Pt structures made on the basis of 0.9, 4, 8, 14 and 18 μm thick YIG epitaxial films. It is found that at frequencies corresponding to the van Hove singularities in the density of states of the MSSW spectrum of the structure, the EMF value generated due to the inverse spin Hall effect increases. This increase is associated with an increase in the spin mixing conductance of the YIG|Pt interface due to an increase in the efficiency of electron-magnon scattering at the frequencies of van Hove singularities in the spin wave spectrum. Keywords: spintronics, spin transport, spin waves, magnon density of states.

Using the inverse spin Hall effect (ISHE), spin pumping by traveling surface waves (MSSW) and backward volume waves (BVMSW) in YIG/Pt microstructures has been experimentally studied. It has been discovered that the frequency dependence of the emf UISHE(f), generated due to the ISHE, in the case of BVMSW is characterized by a maximum near the frequency of the long-wave (f0) spectrum boundary. In the case of a MSSW, the dependence UISHE (f) exhibits maxima both at the frequency f0 and at the frequency fs of the short-wave boundary of the MSSW spectrum. The indicated differences in the dependences UISHE (f) for MSSW and OOMSW are explained by the difference in the functions of the density of states of spin waves in the spectrum of MSSW and BVMSW.

The purpose of this work is to study the influence of four-magnon (4M) parametric instability on spin pumping by dipole-exchange magnetostatic surface waves (MSSW) with the help of the inverse spin Hall effect (ISHE) in structures based on yttrium-iron garnet (YIG) and platinum (Pt). Methods. The experiments were carried out using the delay line structures based on YIG(900 nm)/Pt(9 nm) where electromotive force (EMF) induced by ISHE demonstrates a growth at the frequencies of the resonant interaction between MSSW and volume exchange modes. The frequency dependencies of the amplitude and phase for the delay line structure and EMF (𝑈(𝑓)) from the platinum layer were studied as a function of the MSSW power. Results. It was shown that the resonant EMF growth at the frequencies of dipole-exchange resonances is caused by the presence of Van Hove singularities in the density of states for spin waves at such frequencies that leads to an increase in the efficiency of electron-magnon scattering at the YIG–Pt interface. A growth in MSSW power beyond the threshold of 4M instability development results in a “smoothing” of resonant particularities in the EMF frequency dependence 𝑈(𝑓) that can be explained by decreasing efficiency of spin pumping due to destruction of dipole-exchange resonances and related singularities in the density of states of spin waves. Conclusion. Obtained results may be of interest for the development of highly sensitive spin current detectors, as well as for the implementation of spintronic devices.

Both inverse spin Hall effect (“interface”) and electron drag by magnons (“bulk”) mechanisms of the electromotive force generation by travelling magnetostatic surface (MSSW) and backward volume (MSBVW) waves in YIG/Pt and YIG/n-InSb microstructures are studied. It is shown that “interface mechanism” plays the main role in YIG/ Pt bilayers, while for YIG/n-InSb structures, electron drag by magnons dominates. Giant oscillations of the voltage caused by inverse spin Hall effect were observed in YIG/Pt structures at frequencies corresponding to resonance interactions of MSSW with the volume exchange modes.

Using micromagnetic simulations, we show the possibility to build spin logic devices based on films of yttrium iron garnet and permalloy where energy channeling of spin waves is achieved due to excitation of focused and narrow-directed wave beams with used antennas. We studied the methods to construct a majority logic gate based on the interference of caustics of spin waves excited with the rectilinear transducers directed at an angle to the in-plane magnetic field. We propose the approach that allows using of amplitude detector to build a truth table and that consists in adding a reference signal with the fixed initial phase to three information signals. The possibility to scale the device on the example of its work in the range of spin waves with micron and submicron wavelengths is demonstrated.

With the help of micromagnetic modeling, we considered particularities of dispersions and amplitude-frequency response of spin waves in a magnonic crystal (MC) formed by etching an array of grooves in the surface of yttrium iron garnet film having linear distribution of magnetization across the thickness from 1.7 kG at the upper surface till 2.02 kG at the bottom. For the geometry of surface magnetostatic spin waves (MSSW), it is shown that nonuniformity of magnetization distribution across the thickness leads to the appearance of frequency regions in the MC spectrum where MSSW propagation is unidirectional and, as the consequence, does not have Bragg resonances. It was also demonstrated that the MC spectrum is determined by the choice of surface used for the formation of the array of grooves. Keywords: spin wave, micromagnetic modelling, film of yttrium iron garnet, magnonic crystal.

With the help of micromagnetic modeling, we considered particularities of dispersions and amplitude-frequency response of spin waves in a magnonic crystal (MC) formed by etching an array of grooves in the surface of yttrium iron garnet film having linear distribution of magnetization across the thickness from 1.7 kG at the upper surface till 2.02 kG at the bottom. For the geometry of surface magnetostatic spin waves (MSSW), it is shown that nonuniformity of magnetization distribution across the thickness leads to the appearance of frequency regions in the MC spectrum where MSSW propagation is unidirectional and, as the consequence, does not have Bragg resonances. It was also demonstrated that the MC spectrum is determined by the choice of surface used for the formation of the array of grooves.

Microwaveguides for spin waves based on yttrium iron garnet films and cross-like structures built on such waveguides are experimentally studied. Effects of the waveguides geometry, location of the microantennas for excitation and detection of the spin waves, and geometry of the waveguides junctions on the spin wave excitation and propagation efficiency are discussed.

The purpose of this work is to find out the influence of three-magnon decay processes on the electromotive force (EMF (U)) generated by propagating magnetostatic surface waves (MSSW) with the help of the inverse spin Hall effect in the “yttrium-iron garnet (YIG) – platinum (Pt)” structure. Methods. The experiments were carried out using the delay line structures based on YIG films with the thickness of 8.8 and 14.6 µm, on the surface of which antennas were formed for MSSWs excitation and reception and a Pt film between antennas. Results. It was shown that the three-magnon parametric instability can significantly change the character of EMF dependences on frequency and on power of MSSW that resulted both from the effect of power limitation and from the participation of parametric spin waves (PSW) and secondary spin waves (SSW) in the processes of electron-magnon scattering on the YIG/Pt border. Conclusion. It was demonstrated that the effect of amplification of EMF generation at the frequencies that are close to the long-wavelength border of the MSSW spectrum is related with the PSW and SSW population of the region of anisotropic dipole-exchange spin waves spectrum, which is characterized by the presence of singularities in the magnon density of states (Van Hove singularities).

The spectrum of spin waves (SW) of tangentially magnetized films of yttrium iron garnet (YIG) with a surface metastructure in the form of gratings of etched grooves with a period close to the film thickness d (~ d) has been experimentally and numerically studied. It has been found that the spectrum of the signal reflected from a microstrip transducer with a width w>> d, located on the YIG film contains absorption lines associated with the excitation of the SW of the surface metastructure. In the case when the magnetic field H and the transducer are oriented along the grooves, the absorption lines of the metastructure are located at frequencies f * near the short-wavelength edge of the spectrum of the surface magnetostatic (Damon--Eshbach) wave f s . It is shown that f * linearly depends on H, which can be used to develop magnetic field sensors. The results of measurements of dependences f * (H) are in qualitative agreement with the results of micromagnetic modeling. Keywords: magnetostatic waves, one-dimensional grating, surface structure, sensor of magnetic field.

The spectrum of spin waves (SW) of tangentially magnetized films of yttrium iron garnet (YIG) with a surface metastructure in the form of gratings of etched grooves with a period Λ close to the film thickness d (Λ~d) has been experimentally and numerically studied. It has been found that the spectrum of the signal reflected from a microstrip transducer with a width w>>d,Λ located on the YIG film contains absorption lines associated with the excitation of the SW of the surface metastructure. In the case when the magnetic field H and the transducer are oriented along the grooves, the absorption lines of the metastructure are located at frequencies f* near the short-wavelength edge of the spectrum of the surface magnetostatic (Damon-Eshbach) wave fs. It is shown that f* linearly depends on H , which can be used to develop magnetic field sensors. The results of measurements of dependences f* (H) are in qualitative agreement with the results of micromagnetic modeling.

Using micromagnetic simulations, we show the possibility to build spin logic devices based on films of yttrium iron garnet and permalloy where energy channeling of spin waves is achieved due to excitation of focused and narrow-directed wave beams by used antennas. We studied the methods to construct a "majority" logic gate based on the interference of caustics of spin waves excited by the rectilinear transducers directed at an angle to the in-plane magnetic field. We propose an approach when adding a reference signal with fixed initial phase to three information signals allows to use an amplitude detector at the output of the device to built a truth table. The possibility to scale the device on the example of its work in the range of spin waves with micron and submicron wavelengths is demonstrated. Keywords: spin waves, magnetic field, ferromagnetic films, permalloy.

Both inverse spin Hall effect (“interface”) and electron drag by magnons (“bulk”) mechanisms of the electromotive force generation by travelling magnetostatic surface (MSSW) and backward volume (MSBVW) waves in YIG/Pt and YIG/n-InSb microstructures are studied. It is shown that “interface mechanism” plays the main role in YIG/ Pt bilayers, while for YIG/n-InSb structures, electron drag by magnons dominates. Giant oscillations of the voltage caused by inverse spin Hall effect were observed in YIG/Pt structures at frequencies corresponding to resonance interactions of MSSW with the volume exchange modes.

Topic. Micromagnetic modeling of the propagation of backward volume magnetostatic waves (MSBVW) beams, excited by an antenna, placed in the center of yttrium iron garnet (YIG) film, has been carried out. Aim. To explore MSBVW-beam focusing with an increase in the amplitude of the exciting field at the antenna under conditions when only four-magnon (4M) processes are allowed for the MSBVW. Methods. The problem was solved using micromagnetic modeling by the finite-difference method solving the Landau-Lifshitz equation using the OOMMF software package. Results. It is shown that, depending on the position of the signal frequency in the MSBVW spectrum, an increase in the amplitude of the input signal above a certain threshold can lead to both the effect of wave beam focusing due to the development of modulation instability and the spatiotemporal chaotization of the amplitude distribution in the beam due to 4M decay processes. Changing of MSBVW-beam instability character at the frequency variation is associated with a change in the angular spectrum width of the beam and interaction between MSBVW and so-called "width" modes of the film. The obtained results can be used to analyze the effects of the propagation of nonlinear spin waves in YIG film waveguides.

Background and Objectives: Magnetic thin film waveguides of a finite width are considered as the main building blocks for magnonic circuits where the magnetostatic waves are the information carriers. The purpose of this study is to investigate experimentally the effects of the waveguides width, position of microantennas for excitation and detection of the magnetostatic waves, coupling between the waveguides on excitation and transmission characteristics of the magnetostatic waves for the waveguides with the width of ~10 μm based on an yttrium iron garnet film (material that has the lowest magnetostatic wave damping among all known magnetic materials). Materials and Methods: A set of the microwaveguides with the specified width of 15, 10 and 5 μm and with different position of the microantennas integrated with the waveguide as well as systems of two close parallel waveguides with the microantennas was fabricated out of 0.9 μm thick yttrium iron garnet film using photolithography, ion etching and magnetron sputtering. Measurements of the transmission and reflection coefficients as a function of the frequency were performed by a vector network analyzer along with a microwave probe station. The bias field was applied tangentially along or perpendicular to the waveguide. Results and Conclusions: It is found that the used technology provided ~70° tilt of the waveguides sidewalls from the vertical direction. It is also revealed that placing the microantennas near the ends of the waveguides reduces the efficiency of excitation of the long-wavelength part of the magnetostatic waves spectrum. In addition, such an arrangement of antennas was characterized by the absence of the features associated with the excitation of the magnetostatic wave width modes. The latter effect can be used for filtering the width modes if necessary. It is shown that, for ~15 μm wide waveguides based on 0.9 μm thick yttrium iron garnet film, there is a significant (~0.5 GHz) overlap of the spectra of the fundamental modes of magnetostatic surface wave and magnetostatic backward volume wave in transversely and longitudinally magnetized microwaveguides, respectively, at the bias field in the range of 0.5–1.5 kOe. This width can be considered close to optimal for constructing structures from orthogonal waveguides based on such thick yttrium iron garnet films. A further decrease in the width leads to an undesirable decrease in the transmission coefficient. In addition, in this case, the shape anisotropy effect can be excessively strong and move a part of the magnetostatic surface and backward volume waves spectra, narrowing the region of their overlap. It is also shown that for two parallel microwaveguides with a width and distance between them Твердотельная электроника, микро- и наноэлектроника 251 of ~15 μm, the excitation of the magnetostatic wave in one of them leads to energy transfer to the adjacent waveguide with an efficiency of ~ -10–15 dB due to the coupling between the waveguides. This effect must be taken into account when miniaturizing magnonic networks.