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Quantum computing, quantum communication, and quantum networks rely on hybrid quantum systems operating in different frequency ranges. For instance, the superconducting qubits work in the gigahertz range, while the optical photons used in communication are in the range of hundreds of terahertz. Due to the large frequency mismatch, achieving the direct coupling and information exchange between different information carriers is generally difficult. Accordingly, a quantum interface is demanded, which serves as a bridge to establish information linkage between different quantum systems operating at distinct frequencies. Recently, the magnon mode in ferromagnetic spin systems has received significant attention. While the inherent weak optomagnonic coupling strength restricts the microwave‐to‐optical photon conversion efficiency using magnons, the versatility of the magnon modes, together with their readily achievable strong coupling with other quantum systems, endow them with many distinct advantages. Here, the magnon‐based microwave‐light interface is realized by adopting an optical cavity with adjustable free spectrum range and different kinds of magnetostatic modes in two microwave cavity configurations. By optimizing the parameters, a conversion efficiency of 1.75×10−8$1.75\times 10^{-8}$ with bandwidth of 24 MHz is achieved. The impact of various parameters on the microwave‐to‐optics conversion is analyzed. The study provides useful guidance and insights to further enhancing the microwave‐to‐optics conversion efficiency using magnons. [ABSTRACT FROM AUTHOR]

Ni 0.6 Zn 0.4 Fe 2 O 4 (NZF-Zn 0.4) ferrites with different Al–Si–B–Pb (ASBP) glass additions were synthesized via a solid-phase reaction method at 1175 °C. The inclusion of ASBP-glass significantly enhances the grain size, density, shrinkage, and magnetic properties of NZF-Zn 0.4 ferrites without introducing impurity phases. The prepared NZF-Zn 0.4 -1 wt%ASBP ferrites not only exhibit appropriate radial shrinkage but also possess a dense microstructure and outstanding magnetic properties. Subsequently, Y 2.4 Bi 0.5 Al 0.1 Fe 3 O 4 (YIG-Al 0.1) ferrites and NZF-Zn 0.4 -1 wt%ASBP ferrites were chosen as the outer rings and inner cores, respectively. Tightly interconnected YIG-Al 0.1 /NZF-Zn 0.4 –1wt.% ASBP ferrite composite substrates were successfully co-fired within the temperature range of 1175 °C–1225 °C following co-pressing. Furthermore, YIG-Al 0.1 /NZF-Zn 0.4 -1 wt%ASBP composite substrates, co-fired at 1175 °C, exhibit a lack of impurity phases in the interface region, minimal element diffusion, and exceptional electromagnetic properties (NZF-Zn 0.4 -1 wt%ASBP: M s = 81.88 ± 0.05 emu/g; YIG-Al 0.1 : ε r = 18.28 ± 0.05@11.17 GHz, tanδ = 3.14 ± 0.55 × 10−4, M s = 21.62 ± 0.55 emu/g). The wide co-firing temperature range of YIG-Al 0.1 /NZF-Zn 0.4 -1 wt%ASBP composite substrates significantly enhances the shrinkage matching rate of two-phase ferrites, and its exceptional electromagnetic properties hold significant potential for applications in RF band circulators. [ABSTRACT FROM AUTHOR]

A study of spin wave spectra in a two-layer structure of iron–yttrium garnet (YIG) with different magnitudes of the saturation magnetizations of the layers has been carried out. Different modes of spin wave propagation (reciprocal, nonreciprocal, single-wave) depending on the type of structure and width of the central waveguide are investigated. The classification of spin wave spectra is carried out, and the class of guided, outgoing, and edge spin modes is identified. In particular, it is shown that in a system of planar magnetic comb-type LS-type microwaveguide tubes with periodic boundary conditions, two non-contiguous frequency regions of existence of guided modes of the central waveguide are observed for a width w of the central waveguide. Two adjacent frequency regions exist in the system of planar magnetic comb-type HS-type microwaveguide tubes at any values of the width of the central waveguide: in the high-frequency region, the mode with outflowing modes of the structure is realized, while in the low-frequency region, the mode with guided modes of the central waveguide is realized. It is shown that in systems of both types in the region of strongly inhomogeneous magnetic fields there can exist modes of boundary waves having a mutual character of propagation. The results obtained can be used to expand and clarify the physics of wave processes in complicated magnetic structures. [ABSTRACT FROM AUTHOR]

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 coupling with acoustic thickness modes of various polarizations are studied. Acoustic spin waves and spin pumping are detected by simultaneous frequency-field mapping of the inverse spin Hall effect voltage and the resonant frequencies of thickness extensional modes. In the parametric range of frequencies and fields, acoustic spin pumping induced by both shear and longitudinal polarization modes was observed. Linear acoustic spin waves are excited only by shear thickness extensional modes because longitudinal acoustic waves do not couple with the magnetic subsystem in linear regime. [ABSTRACT FROM AUTHOR]

This work presents a new methodology for fabrication of membrane-assisted elongated YIG nanostructures through the sol-gel method using low-cost materials, and the estimation of the average size of the geometries formed within the pores through ferromagnetic resonance measurements. A precursor solution was deposited on the internal surface of porous aluminum oxide membrane, using an assembly consisting of a vacuum system coupled to an apparatus, which assists in the entry of the used precursor solution, breaking the barriers related to the existing surface tension, with subsequent heat treatment to form the single phase of yttrium iron garnet (YIG). The data collected by X-ray diffraction and Raman spectroscopy indicated this result. The study of the contact angle of the precursor solution and the alumina template indicated great compatibility, an angle of 35.4°. SEM analysis showed that elongated structures were deposited inside the pore's walls, with different lengths up to 3 micrometers and the EDS analysis showed the presence of the main elements of the YIG phase. The Kittel's equation and FMR spectral data were used to estimate the mean size of the elongated nanostructures. We found six different size categories with 1856, 1768, 1661, 1588, 1570, 1498 nm. The methodology proved to be efficient for the characterization of elongated YIG nanostructures, becoming a perspective of future applications. Highlights: Setup for the infiltration of the alumina membrane with the YIG precursor was proposed. Elongated YIG structures were obtained with diverse potential applications. The FMR was used to estimate the mean size of elongated YIG structures. [ABSTRACT FROM AUTHOR]

The hybrid high overtone bulk acoustic wave resonators (HBARs) consisting of a piezoelectric film transducers and gallium gadolinium garnet substrates with yttrium iron garnet films (YIG-GGG-YIG) are used for experimental excitation and detection of acoustically driven spin waves (ADSWs). Two types of HBAR transducers made of Al-ZnO-Al films (differed through the electrodes’ geometry) were deposited onto YIG-GGG-YIG trilayers with different YIG film thicknesses and doping levels and served for excitation of multimode HBAR at gigahertz frequencies. ADSWs were detected by measuring the shifts of resonant HBAR modes in a tangential external magnetic field when the conditions for magnetoelastic resonance (MER) were satisfied. It was shown that the design of the transducer with a continuous bottom electrode provides all acoustical excitation of spin waves (pure ADSWs), suppressing the additional inductive magnetic dynamics excitation due to the electrodes’ geometry. The theoretical study of the HBAR spectrum in a magnetic field showed that the resonance harmonics in the MER region can either almost continuously transfer from one to another, or decay and form an evident magnetoelastic gap. In this case, the shift of resonant frequencies can achieve several intermodal distances. The results obtained are important for applications of HBAR-based devices in spintronics and magnonics.

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Y 2.5- x Bi 0.5 Al x Fe 5 O 12 (YIG-Al x) ceramics have been synthesized at 1175 ℃ by the solid-state reaction method. The effects of the co-doped Bi3+, Al3+ ions on the phases, micromorphology, and dielectric and magnetic properties of the yttrium iron garnets (YIG) were investigated. Excessive introduction of Al3+ ions led to the collapse of the YIG lattice and precipitation of the Bi3+ and Fe3+ ions; while moderate Al3+ doping improved the dielectric properties, but not the saturation magnetization. The YIG-Al 0.2 ceramics proved to have particularly good electromagnetic properties (ε r = 18.34 ± 0.05@11.19 GHz, tan δ = 3.09 ± 0.55 × 10−4, M s = 19.82 ± 0.55 emu/g). Additionally, tightly bonded Y 2.3 Bi 0.5 Al 0.2 Fe 5 O 12 /Ni 0.8 Zn 0.2 Fe 2 O 4 (YIG-Al 0.2 /NZF) composite substrates were prepared by co-firing at 1175 ℃. The composite substrates exhibited superior electromagnetic properties (YIG-Al 0.2 : ε r = 18.37 ± 0.05@11.15 GHz, tan δ = 3.08 ± 0.55 × 10−4, M s = 21.09 ± 0.55 emu/g; NZF: M s = 67.5 ± 0.55 emu/g), which were slightly affected by the diffusion of Ni and Zn from the NZF. Our findings show that YIG-Al 0.2 /NZF substrates have great potential for use as RF band circulators. • The YIGs appropriately doped with Bi3+-Al3+ ions has good dielectric properties. • The co-pressed and co-fired techniques were applied to the composite substrates. • The YIG-Al 0.2 /NZF ferrites composite substrates possess high electromagnetic properties. • Diffusion of Fe3+ ions of the YIG-Al 0.2 /NZF ferrites composite substrates was small. [ABSTRACT FROM AUTHOR]

The hybrid high overtone bulk acoustic wave resonators (HBARs) consisting of a piezoelectric film transducers and gallium gadolinium garnet substrates with yttrium iron garnet films (YIG-GGG-YIG) are used for experimental excitation and detection of acoustically driven spin waves (ADSWs). Two types of HBAR transducers made of Al-ZnO-Al films (differed through the electrodes' geometry) were deposited onto YIG-GGG-YIG trilayers with different YIG film thicknesses and doping levels and served for excitation of multimode HBAR at gigahertz frequencies. ADSWs were detected by measuring the shifts of resonant HBAR modes in a tangential external magnetic field when the conditions for magnetoelastic resonance (MER) were satisfied. It was shown that the design of the transducer with a continuous bottom electrode provides all acoustical excitation of spin waves (pure ADSWs), suppressing the additional inductive magnetic dynamics excitation due to the electrodes' geometry. The theoretical study of the HBAR spectrum in a magnetic field showed that the resonance harmonics in the MER region can either almost continuously transfer from one to another, or decay and form an evident magnetoelastic gap. In this case, the shift of resonant frequencies can achieve several intermodal distances. The results obtained are important for applications of HBAR-based devices in spintronics and magnonics. [ABSTRACT FROM AUTHOR]

In this study, MnZn ferrites with added YIG nanoparticles were developed for MHz frequency applications. The effect of the magnetic YIG additive on the power loss, initial permeability, and cutoff frequency of MnZn ferrites was investigated. A small quantity of added YIG effectively reduces the power loss and concurrently increases the initial permeability. Compared to the results for the MnZn ferrite with no added YIG, the optimal MnZn ferrite with 600 ppm added YIG exhibits a reduction in the power loss at 25°C of 56.4% and 36.6% at 1 MHz/50 mT and 3 MHz/10 mT, respectively, and a 13.9% increase in the initial permeability. This sample also exhibits a good stability of the power loss against temperature. The power loss remains below 205 kW/m3 over temperatures ranging from 25 to 140°C. The effect mechanism of YIG addition on the magnetic properties of MnZn ferrites was studied. An analysis based on the equivalent circuit model showed that the reduction in the eddy current loss and power loss mainly results from the increase in the grain boundary resistance caused by the addition of highly resistive YIG. [ABSTRACT FROM AUTHOR]

We present a theoretical study about the cation distribution and their effect on the physical properties of Ni-doped YIG system, based on a phenomenological model, the generalized Kapustinskii equation, and the single ion contribution to the saturation magnetization and cubic anisotropy constant. From the calculated reticular energy values ( U ret ) it was possible to determine the more probable valence state configuration, corresponding with the coexistence of 3+ and 2+ oxidation states for Fe ions, the 2+ oxidation state for Ni, and oxygen vacancies presence. In addition, from the occupation probability values, it was demonstrated that Ni2+ and Fe2+ cations prefer to occupy the octahedral sites, reflecting on the saturation magnetization (Ms) and cubic anisotropy constant (K1) behaviors. The theoretical results of Ms and K1 were compared with the experimental values, showing a reasonable correspondence, considering the simplicity of the presented phenomenological model. [ABSTRACT FROM AUTHOR]

Article Highlights High transmission of edge spin waves through a vertex domain wall in triangular dots. Dependence in the propagation on the local topology of the vertex domain wall. Resonant interaction between the bulk and the local domain wall spin wave modes in the magnetic nanostructure.

Y 3 Fe 5 O 12 (YIG) 1-x /Carbon-Black(CB) x (0.00≤x≤1.00; 0.25 steps) coated with polyaniline (PANI), forming a core-shell structure, were synthesized by in-situ polymerization following sol-gel and solid-state reactions. The crystalline, surface morphology and magnetic properties of YIG 1-x /CB x and PANI@YIG 1-x /CB x hybrid composites were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM), respectively. Electromagnetic wave (EMW) absorbing properties were investigated by measuring dielectric parameters in the 2–18 GHz frequency range. The reflection loss (RL), impedance matching, and loss tangent were studied in detail. The electromagnetic wave absorbing mechanisms were discussed by considering dielectric and magnetic losses, as well as microstructural properties of the samples. The EMW absorbing performance of the YIG 1-x /CB x composites showed a broadband absorption property (7.0 GHz bandwidth at −10 dB reflection loss value) in YIG 0.75 /CB 0.25 composite. When the composites are covered with conductive PANI, the EMW absorbing performance is enhanced in terms of RL (minimum −36.5 dB) and effective absorption bandwidth (EAB) (maximum 10.2 GHz at −10 dB) values due to increasing scattering probability, interfacial polarization and conduction loss of the penetrated EMW. The results showed that a wider absorption frequency range could be obtained by coating PANI on YIG/CB composite. • EMW absorbing performance of YIG/CB composite is enhanced by PANI coating. • Minimum reflection loss is achieved as −36.5 dB in PANI@YIG 0.25 /CB 0.75 hybrid composite. • Excellent EMW absorbing bandwidth at −10 dB is observed as 10.2 GHz in PANI@ YIG 0.5 /CB 0.5 hybrid composite. [ABSTRACT FROM AUTHOR]

This research article presents the current challenges faced by our ecosystem due to depletion and insufficient fresh water bodies. In this current work, a novel holistic approach for the removal of toxic cadmium heavy metal ion from water using yttrium iron garnet is demonstrated. The impact of annealing temperature on the formation of garnet ferrite phase was investigated. The crystal structure analysis was investigated using X-ray diffraction (XRD) and further analyzed using Rietveld refinement technique. The surface morphology and functional groups were analyzed using high-resolution scanning emission microscopy (HR-SEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy in detail. The magnetic property variation with respect to annealing temperatures was assessed from the data acquired from vibrating sample magnetometer (VSM) studies done at room temperature. X-ray photoelectron spectroscopy (XPS) chemical analysis technique was used to study the oxidation states of cations in the sample. To our knowledge, the utilization of yttrium iron garnet (YIG) as a magnetic adsorbent is extremely rare. So, in this article, we report the nature, important characteristics, and advantages of utilizing YIG nanoparticles for the eradication of cadmium for the treatment of water using atomic adsorption spectroscopy (AAS) technique. The experimental data was interpreted using adsorption isotherm modelling such as Langmuir and Freundlich isotherms. [ABSTRACT FROM AUTHOR]

High-quality single-phase YIG films prepared by metallo-organic decomposition (MOD) and suitable for the fabrication of ordered nanostructures using a focused ion beam are presented in this work. The YIG films were deposited both on Si and SiO2 substrates and the cleaning process of the substrate was evaluated as a parameter influencing the film homogeneity. X-ray diffraction and Raman spectroscopy data revealed that a single YIG resulted in all experiments. SEM and AFM showed that films are crack-free with porous morphology and the roughness is smaller than Rq < 0.2 nm. The methodology is scalable and low cost if compared to methods previously described in the literature. The resulting nanostructures are promising for studies in spintronics with thickness between 135 and 180 nm. [ABSTRACT FROM AUTHOR]

Abstract A multiband magneto-dielectric resonator antenna with cylindrical geometry is proposed in this paper. The resonator is composed of yttrium iron garnet (YIG) with chemical composition Y3Fe2(FeO4)3. The final structure is built on a low-cost FR4 dielectric substrate. With only one resonator, the antenna is able to resonate in three distinct controlled frequency bands. These are the three propagation modes HEM11δ, TE01δ, and TM01δ, which are possible to be independently controlled at each input port of the resonator antenna. The resonator’s port was suitable designed to feed specific modes of the antenna using microstrip lines placed judiciously to excite each mode. Analytic, numerical, and experimental studies were performed and, after optimization, the final antenna design was obtained. The obtained simulated and measured S-parameters results are below -10 dB at the resonance frequencies 5.75 GHz, 6.86 GHz, and 8.37 GHz. The corresponding measured bandwidths are 370 MHz, 120 MHz, and 1060 MHz, respectively. The antenna has a total size of 32.5 × 32.5 × 8.35 mm3. Measured radiation patterns and gain are also presented and show good agreement when compared to simulated results.

Chiral spin textures have emerged as a captivating class of topological matter. These intriguing structures harbor localized and topologically protected magnetic textures, rendering them promising candidates for novel spintronic applications. Here, the emergent chiral spin textures in an iron garnet with nanodisk configuration have been micromagnatically simulated based on the Landau-Lifshitz-Gilbert equation (LLG) of COMSOL Multiphysics. The modification of magnetic spin texture in the considered iron garnet has been controlled by introducing the interfacial Dzyaloshinskii-Moriya interaction (I-DMI) and spin alignment constraints as locally pinned spins and curvilinear defects at edges. These boundary conditions induced interesting chiral textures not commonly observed in such iron garnet due to its centrosymmetric crystal structure. The simulation results showed the presence of two distinct regions of spin texture: inside and outside the pinning boundary. By systematically varying the DMI strength (D) with the size of the pinning boundary (R pin) and the number of defects (N def), the emerging chiral spin textures have been explored and reported, including the existence of ramified helical stripes, skyrmions, and skyrmions-like textures such as elongated skyrmions, chiral horseshoe domains, biskyrmions and target skyrmions (TSk) (2π-TSk and 3π-TSk). Also, it has been reported that various collapses occur in the final spin texture states, leading to the transition from one state to another when varying the values of R pin and N def with D. [ABSTRACT FROM AUTHOR]

In this work, we investigate the structural and dynamic magnetic properties of yttrium iron garnet (YIG) films grown onto gadolinium gallium garnet (GGG) substrates with thin platinum, iridium, and gold spacer layers. Separation of the YIG film from the GGG substrate by a metal film strongly affects the crystalline structure of YIG and its magnetic damping. Despite the presence of structural defects, however, the YIG films exhibit a clear ferromagnetic resonance response. The ability to tune the magnetic damping without substantial changes to magnetization offers attractive prospects for the design of complex spin-wave conduits. We show that the insertion of a 1-nm-thick metal layer between YIG and GGG already increases the effective damping parameter enough to efficiently absorb spin waves. This bilayer structure can therefore be utilized for magnonic waveguide termination. Investigating the dispersionless propagation of spin-wave packets, we demonstrate that a damping unit consisting of the YIG/metal bilayers can dissipate incident spin-wave signals with reflection coefficient R < 0.1 at a distance comparable to the spatial width of the wave packet. [ABSTRACT FROM AUTHOR]

Virtual materials design requires not only the simulation of a huge number of systems, but also of systems with ever larger sizes and through increasingly accurate models of the electronic structure. These can be provided by density functional theory (DFT) using not only simple local approximations to the unknown exchange and correlation functional, but also more complex approaches such as hybrid functionals, which include some part of Hartree–Fock exact exchange. While hybrid functionals allow many properties such as lattice constants, bond lengths, magnetic moments and band gaps, to be calculated with improved accuracy, they require the calculation of a nonlocal potential, resulting in high computational costs, that scale rapidly with the system size. This limits their wide application. Here, we present a new highly-scalable implementation of the nonlocal Hartree-Fock-type potential into FLEUR—an all-electron electronic structure code that implements the full-potential linearized augmented plane-wave (FLAPW) method. This implementation enables the use of hybrid functionals for systems with several hundred atoms. By porting this algorithm to GPU accelerators, we can leverage future exascale supercomputers which we demonstrate by reporting scaling results for up to 64 GPUs and up to 12,000 CPU cores for a single k-point. As proof of principle, we apply the algorithm to large and complex iron garnet materials (YIG, GdIG, TmIG) that are used in several spintronic applications.

We report a study on the interfacial antiferromagnetic coupling between ferrimagnetic TbIG/YIG thin films. TbIG/YIG bilayers are grown on YAG (110) substrates. The crystal structure and magnetic properties of the films are characterized. The temperature and directional dependences of the antiferromagnetic coupling effect are observed at low temperatures. This work enriches the magnetic research of ferrimagnetic oxide films with complex structures, providing new ideas for the design of antiferromagnetically coupled spintronics devices. [ABSTRACT FROM AUTHOR]

YIG with its short name of Yttrium Iron Garnet (Y₃Fe₅O₁₂) is one of the materials that have been working intensively in recent years due to its promising applications in microwave communication systems and magneto-optical devices. Today, YIG thin films are grown on the Gallium- Gadolinium-Garnet substrates with the short name of GGG. However, because the cost of GGG substrate is very high which restricts the production of YIG films economically. Our preliminary studies have shown that it is possible to grow YIG thin film on the quartz substrate. In this study, quartz substrate was used instead of GGG substrate which meets lower cost and expected performance. YIG thin films were grown on quartz substrate by spin-coating method. The surface homogeneity of YIG thin film coated samples produced under suitable production conditions was provided. YIG films grown on quartz substrate were found to be crystallized in a single-phase cubic garnet structure. In addition, Ni doped YIG films were grown similar technique. The magnetic field applied between -5000 Oe and +5000 Oe, magnetization values were measured and hysteresis curves were obtained.

The spin Hall magnetoresistance (SMR) at Pt/ Y3Fe5O12(YIG) interfaces with (100)-, (110)- and (111)-oriented YIG films was studied. Before that, high-quality YIG films were fabricated on Gd3Ga5O12 (GGG) substrates by pulsed-laser deposition and the structure, magnetic property and damping of YIG films with different crystallographic orientations were compared and analyzed. By angle-dependent magnetoresistance (ADMR) measurements in neighboring Pt layer of YIG films, an anisotropy of SMR was observed. The spin mixing conductance (SMC) at different Pt/YIG interfaces was calculated according to the model of SMR. It was found that Pt/YIG (100) and Pt/YIG(110) interfaces have larger SMC than that of Pt/YIG(111) interface due to the relatively larger surface roughness, which could provide a reference for optimizing the performance of magnetic transport property in magnonic devices involving Pt/YIG interface. [ABSTRACT FROM AUTHOR]

In this work, a kind of magnetic photonic crystal fiber (MPCF) design based on yttrium iron garnet (YIG) structure filled with magnetic fluid (MF) is presented. In order to improve the magneto-optical (MO) properties of isolator devices, a numerical study has been developed to investigate the non-reciprocal TE-TM mode conversion. This technique consists in producing, under the influence of a magnetic field parallel to the direction of propagation, a coupling between the modes. The influence of gyrotropy and MF infiltration at different magnetic nanoparticle volume fraction concentrations is investigated. The results revealed that the mode conversion efficiency (Rm) increases with the increase of the MF concentration, while modal birefringence (∆n) is inversely proportional to its increase. Thus, the higher concentration provides the best results. For MF concentration and gyrotropy equal respectively to 1.75% and 0.0125, Rm is improved to over 93%, and ∆n is reduced to close to 10–6. Whereas, Rm decreases to 89.59 and ∆n increases to 6 × 10–6 for MF concentration equal to 0.25%. From these results, it can be seen that this MPCF filled with MF concentration equal to 1.75% is well suited to the design of MO isolators. [ABSTRACT FROM AUTHOR]

A multiband magneto-dielectric resonator antenna with cylindrical geometry is proposed in this paper. The resonator is composed of yttrium iron garnet (YIG) with chemical composition Y3Fe2(FeO4)3. The final structure is built on a low-cost FR4 dielectric substrate. With only one resonator, the antenna is able to resonate in three distinct controlled frequency bands. These are the three propagation modes HEM11d, TE01d, and TM01d, which are possible to be independently controlled at each input port of the resonator antenna. The resonator's port was suitable designed to feed specific modes of the antenna using microstrip lines placed judiciously to excite each mode. Analytic, numerical, and experimental studies were performed and, after optimization, the final antenna design was obtained. The obtained simulated and measured S-parameters results are below -10 dB at the resonance frequencies 5.75 GHz, 6.86 GHz, and 8.37 GHz. The corresponding measured bandwidths are 370 MHz, 120 MHz, and 1060 MHz, respectively. The antenna has a total size of 32.5 × 32.5 × 8.35 mm2. Measured radiation patterns and gain are also presented and show good agreement when compared to simulated results. [ABSTRACT FROM AUTHOR]

Realizing room-temperature slow light is of fundamental importance in physics and may promote the practical applications of slow light in information storage and optical communication. Here, we propose a feasible way to realize room-temperature slow light based on magnon-polaritons in a coupled cavity magnon-photon system, in which the cavity microwave photons strongly coupling with the magnons in a small-scale magnetic insulator yttrium-iron-garnet (YIG, Y3Fe5O12). We find that the generation of slow light does not require the harsh conditions of ultra-low temperature, and the magnitude of the group delay can be regulated by adjusting the external magnetic field. Furthermore, the transformation between the fast and slow light can be achieved by controlling the magnon-photon coupling strength. Based on the current experimental condition, we believe that the proposed scheme of room-temperature slow light will be highly accessible in experiments. The potential applications range from enhancing magnon-photon interaction to designing an optical communication network.

An analogous Kerr nonlinearity of a magnon would be a subject of interest and plays an important role in researching the interactions between the magnons and photons. Using the experimentally achievable parameters, we present a perturbed approach to deal with the nonlinear dynamics of magnon polaritons and obtain analytical formulas to understand the physical picture of magnon induced second-order sideband generation. We prove that this effect is modified by either adjusting the microwave drive power and the Kerr coefficient or the coupling strength. The numerical calculations of the system dynamic equations show an excellent agreement with our analytical results. In particular, an optimal parameter area is proposed, in which the signal of magnon-induced second-order sideband generation is robust. In addition to providing insight into the nonlinear interactions between the magnons and photons, our results may also offer attractive new prospects for the development of the magnon frequency comb.

Growing homogeneous-phase YIG grains on Si substrates through a low-cost sol-gel route is crucial to the integration of patterned YIG on a Si-based photonic platform. Here, the fabrications of both YIG powders and films are compared for studying their difference in phase transition. A buffered layer of YIP is found necessary for the complete conversion of Y 2 Fe 4 O 9 phase to YIG phase on Si substrates. Through the optimization of experimental factors, homogeneous-phase YIG grains with micron-scale size and rectangle profile are fabricated on the Si substrate. The narrow and strong Micro-Raman peaks of the as-grown grain reveal the crystal lattice with high perfection while slight shifts of some Raman peaks indicate the residual stress induced by repeated annealing. The magneto-optical property of the YIG grain, characterized on a micron scale by using a home-made system, is found comparable to that of the commercially epitaxial YIG film on a GGG substrate. [ABSTRACT FROM AUTHOR]

In this work, we investigate the structural and dynamic magnetic properties of yttrium iron garnet (YIG) films grown onto gadolinium gallium garnet (GGG) substrates with thin platinum, iridium, and gold spacer layers. Separation of the YIG film from the GGG substrate by a metal film strongly affects the crystalline structure of YIG and its magnetic damping. Despite the presence of structural defects, however, the YIG films exhibit a clear ferromagnetic resonance response. The ability to tune the magnetic damping without substantial changes to magnetization offers attractive prospects for the design of complex spin-wave conduits. We show that the insertion of a 1-nm-thick metal layer between YIG and GGG already increases the effective damping parameter enough to efficiently absorb spin waves. This bilayer structure can therefore be utilized for magnonic waveguide termination. Investigating the dispersionless propagation of spin-wave packets, we demonstrate that a damping unit consisting of the YIG/metal bilayers can dissipate incident spin-wave signals with reflection coefficient R < 0.1 at a distance comparable to the spatial width of the wave packet.

This work presents a magneto‐dielectric cylindrical resonator antenna (MDCRA) based on the YIG matrix, presenting two relevant new features. The first feature is to allow independent control of modes and the second one a dual‐band response. The MDCRA has two distinct propagation modes HEM11δ (5.78 GHz) and TE01δ (6.75 GHz) which can be controlled independently. The magneto‐dielectric resonator is manufactured using the magnetic ceramic material originated from the ferrites (Yttrium Iron Garnet, YIG) of composition Y3Fe2(FeO4)3, which is placed on low cost FR4 dielectric substrate. The microstrip feeding mechanism design assures the decoupling of the two modes by using orthogonal microstrip lines. The proposed MDCRA antenna was designed, fabricated, and then characterized inside an anechoic chamber. The scattering S‐parameters were analyzed in the frequency bands from 4.9 GHz to 7.6 GHz, with results within the expected range. The 2‐D and 3‐D radiation patterns are also presented. The validation was carried out with analytical mathematical equations, numerical formulation using the commercial CST Studio software, and experimental results, which shows a good agreement. [ABSTRACT FROM AUTHOR]

Yttrium Iron Garnet (YIG) ferrites thin films having compositional formula Y 3 Ga x Fe 5-x O 12 , where (x = 0, 1, 2, 3, 4) are synthesized by sol gel dip coating technique. XRD, SEM and VSM characterizations are employed to explore structural, morphological and magnetic properties, respectively. XRD showed that Ga is completely doped in YIG and not formed any cluster or other phase with YIG. SEM confirmed the formation of agglomeration of YIG particles. Magnetic parameters like coercivity, remnant squareness, saturation magnetization, magnetic moment, anisotropy constant, initial permeability Y–K angles and microwave frequency were calculated of these films. The coercivity and moderate magnetization suggested that fabricated ferrite films are highly applicable in electromagnetic microwave absorption and frequency agile antenna for wireless communication. [ABSTRACT FROM AUTHOR]

Samarium substituted yttrium iron garnet powders, Y3−xSmxFe5O12 (x = 0, 0.1, 0.2, 0.4, 0.6, 1), were prepared by Co-precipitation method. The phase structure of synthesized powders examined using X-ray diffraction confirmed the foundation of the cubic structure. The average crystallite size, of the garnets, decreased by 4.5% with increasing Samarium concentrations. This decrease is confirmed by scanning electron microscope. Fourier transform infra-red spectrophotometer spectra show three noticeable absorption bands. The increase in Samarium concentration causes a slight shift in the absorption bands to lower values. The room temperature magnetization studies were performed using a vibrating sample magnetometer. The obtained results show a decrease of magnetization at high concentration and an increase in coercivity with the increase in Sm concentration. It is concluded that the substitution of Sm enhances the Yttrium iron garnet microwave magnetic material, thus it can be used in high power non-reciprocal microwave devices. [ABSTRACT FROM AUTHOR]

Samarium substituted yttrium iron garnet powders, Y3−xSmxFe5O12 (x = 0, 0.1, 0.2, 0.4, 0.6, 1), were prepared by Co-precipitation method. The phase structure of synthesized powders examined using X-ray diffraction confirmed the foundation of the cubic structure. The average crystallite size, of the garnets, decreased by 4.5% with increasing Samarium concentrations. This decrease is confirmed by scanning electron microscope. Fourier transform infra-red spectrophotometer spectra show three noticeable absorption bands. The increase in Samarium concentration causes a slight shift in the absorption bands to lower values. The room temperature magnetization studies were performed using a vibrating sample magnetometer. The obtained results show a decrease of magnetization at high concentration and an increase in coercivity with the increase in Sm concentration. It is concluded that the substitution of Sm enhances the Yttrium iron garnet microwave magnetic material, thus it can be used in high power non-reciprocal microwave devices. [ABSTRACT FROM AUTHOR]

In the present work, we have studied the competitive effect of Er and Cr dopants on the structural and magnetic properties of yttrium iron garnet (YIG) nanoparticles synthesized by the sol gel method. The YIG single phase was obtained for all samples and the variations of structural parameters were associated to the dopants influence. Fourier transform infrared spectroscopy showed typical absorption peaks of YIG, with small displacements for larger wavenumbers corresponding to vibrational modes (Fe–O) belonging to the tetrahedral sites. The behavior of the Raman vibrational modes as a function of dopant concentration confirms the insertion of Er in dodecahedral sites and Cr in the octahedral and tetrahedral sites. A frequency shifting of some Raman modes was observed as the Cr concentration increased. The powder morphology was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), evidencing agglomerated particles with irregular shapes. The Er and Cr incorporation in YIG promote random fluctuations in the saturation magnetization, coercivity and the magnetocrystalline anisotropy constants of the synthesized compound. [ABSTRACT FROM AUTHOR]

Dy3+ incorporated yttrium iron garnet (Y 3-x Dy x Fe 5 O 12) nanoparticles were fabricated via self-combustion assisted solution gelation route. The mono-phase formation and nanocrystalline nature of the fabricated samples were confirmed through X-ray employed diffraction studies. It demonstrates mono phasic garnet-cubic-spinel lattice formation along with an average particle size varying between 6 and 9 nm. The lattice constant determined via XRD analysis is found within the scope of 12.356 Å to 12.424 Å. The morphological aspects were visualized by the SEM analysis which uncovered the spherical shaped nature of grains with the size in nanometer range. The compositional verification was undertaken with the help of EDAX analysis which ensured the presence of elements in desired proportions. The magnetic parameters were diminished with Dy3+ content x while the magneton number n B increased with increasing Dy3+ content x. The electrical properties were measured using 'two probe technique' with varying temperature. The electrical resistivity diminishes with increment in temperature demonstrating semiconducting conduct. Values of various dielectric parameters show strong frequency dependence. With the increase in frequency, the dielectric parameters get decreases within the scope of 104 Hz–106 Hz. The magnetic, electrical and dielectric conduct of these prepared nanoparticles show its relevance in high frequency device development applications. [ABSTRACT FROM AUTHOR]

Y3Fe5O12 and Y2.8La0.2Fe5 − xAlxO12 (x = 0.0, 0.1, 0.2, and 0.3) nanoferrites have been prepared by the sol-gel auto combustion route followed by sintering at 900 ° C for 3 h. The garnet phase formation has been confirmed by analyzing XRD patterns and also by noting intense bands for Fe-O vibrations in FTIR spectra. The XRD analysis has shown a decreasing trend for lattice parameter, X-ray density, and d-spacing due to the addition of smaller Al3+ ions at tetrahedral sites. The SEM study has shown agglomerated and branched morphology with an average branch width and branch length ranging between 90–140 nm and 537–437 nm, respectively. Enhanced values of saturation magnetization have been observed for all the samples due to the presence of 6.7% of La3+ ions in place of Y3+ ions. However, it decreased due to weakening of superexchange interaction with the addition of Al3+ ions at tetrahedral sites. These nanoferrite powders can be used as a substitute for costly rare earth garnets and also in many high-frequency microwave devices. [ABSTRACT FROM AUTHOR]

In this study, the tape casting and characterization of a yttrium iron garnet (YIG) ferrite thick film was carried out for microwave substrate applications. A high-performance YIG ferrite thick film was developed using a well-dispersed non-aqueous YIG slurry. The resulting green YIG film exhibited a smooth surface and a uniform particle-packing structure with a green density of 3.12 g/cm3. The YIG substrate sintered at 1480 °C exhibited a dense microstructure and good properties with a bulk density of 5.06 g/cm3, dielectric constant (ε r) of 14.2, dielectric loss (tanδe) of 1.8 × 10−4 (10 GHz), saturate magnetization (4π M s) of 168.2 mT, coercive force (Hc) of 0.47 Oe, and ferromagnetic resonance linewidth (Δ H) of 5.2 KA/m. Thus, the YIG casting film developed in this study was found to be suitable for microwave substrate applications. [ABSTRACT FROM AUTHOR]

In the present work experimental data for saturation magnetization at low temperatures, of yttrium iron garnet nanoparticles are different from that expected by the T3/2 Bloch's Law. This result is mainly conditioned by the local atomic disorder induced during the nanoparticles preparation by using the sol gel method. To correctly describe the experimental curves, a fitting using Cojocaru's theory was performed because the model uses geometric and other conditions in agreement with our experimental results. The magnetic ions localized at the nanoparticles surface, outside the crystalline periodicity, are the responsible by the saturation magnetization behavior presented here. [ABSTRACT FROM AUTHOR]

Magnetized ferrites are anisotropic materials used in passive non-reciprocal components. One of the main applications of ferrites at microwave frequencies is the isolation effect. In this work, the non-reciprocal propagation in a ferrite coplanar coupler is studied from simulation results. The proposed structure exhibits a low insertion loss less than 1 dB, and return loss better than 20 dB, with significant non-reciprocal behavior for through propagation. The design of the non-reciprocal coplanar coupler, based on a magnetized transversally ferrite as substrate dielectric material, is presented. The numerical study allows to describe the component physical behavior. As results, a miniature coupler at 12.50 GHz with a non-reciprocal effect in direct access is better than 35 dB has been designed and simulated. [ABSTRACT FROM AUTHOR]

This paper describes the effect of 5-nm thick platinum (Pt), aluminum (Al) and silicon oxide (SiO x) capping layers on the static and dynamic magnetic properties of 400-nm thick polycrystalline YIG films deposited on a Pt buffer layer. Both static and dynamic magnetic properties of Pt capped YIG film are totally different among all YIG films. Namely, the squareness of the magnetization curve for Pt capped YIG film increases, indicating that Pt capped YIG film is magnetically softer than other YIG films. Interestingly, the effective Gilbert damping parameter of Pt capped YIG films is about four times as large as those of other YIG films, and its value is approximately 9.52 × 10−4. However, the value of Gilbert damping is 2.55 × 10−4, 3.46 × 10−4 and 3.85 × 10−4 respectively for no capping, SiOx capping and Al capping samples respectively. This huge change in Gilbert damping parameter is mainly originating from the spin pumping effect, which arises at the interface of a material having strong spin orbit interaction such as Pt. Moreover, the enourmous increase in the value of effective anisotropic field and decrese in effective saturation magnetization indicates interface anisotropy is induced in Pt capped sample. These results suggest that the static and dynamic magnetic properties of YIG film can be controlled by selecting an appropriate capping layer. • Effect of different capping layers on static and dynamic magnetic properties of YIG films have been investigated. • The remanence ratio (M r /M s) of Pt capped YIG film is highest compared to other samples. • Pt capped YIG film shows an enormous increase in the value of effective anisotropic field (H k,eff) and decrease in effective saturation magnetization (4πM s,eff). • The effective Gilbert damping parameter (α eff) of Pt capped YIG films is about four times as large as those of other YIG films. • The static and dynamic magnetic properties can be tuned by choosing proper capping layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electromagnetic properties of YIG were modulated by doping Nd on the Y site and Sn4+-Cu2+ on the Fe site. • The resistivity and dielectric constant of YIG increase with the increasing concentration of Nd ion doping. • The maximum value of the real part of the dielectric constant is achieved for 29.5@200 kHz. Ion doping to regulate the magnetic and dielectric properties of yttrium iron garnet ferrites is highly desirable for microwave devices. This study successfully fabricated Y 3-x Nd x Fe 4.8 Cu 0.1 Sn 0.1 O 12 (x = 0, 0.5, 1.0, 1.5) ceramics, controlling their magnetic and dielectric properties via Nd ion doping. The results indicate that the introduction of Nd ions into the YIG lattice, occupying dodecahedral sites and replacing Y3+ ions, leads to an increase in the lattice parameter. The hysteresis loops demonstrate that as the concentration of Nd ion doping increases, the saturation magnetization initially decreases and then increases. Additionally, the complex impedance and dielectric spectrum analysis reveal that the resistivity and dielectric constant of the material increase with the increasing concentration of Nd ion doping. The real part of the dielectric constant reaches its maximum value, 29.5@200 kHz, at x = 1.5. Consequently, Nd doping concentration effectively controls the crystal structure, microstructure, magnetic, and dielectric properties of garnet ferrite, enhancing its magnetic and dielectric properties and potential application in microwave devices. [ABSTRACT FROM AUTHOR]

• The interfacial balance between Y 3 Fe 5 O 12 and Fe 2 O 3 materials can enhance the microwave absorbing performance. • A correlation between the EMW absorbing and multi-crystal phase content has been observed in Fe 2 O 3 /Y 3 Fe 5 O 12 structure. • Minimum reflection loss is achieved as −19.5 dB with absorption bandwidth as 2.6 GHz in Fe 2 O 3 /Y 3 Fe 5 O 12 sintered at 1000 °C. In this work, the interfacial effect on the electromagnetic wave (EMW) absorbing performance in Y 3 Fe 5 O 12 and Fe 2 O 3 material system synthesized by one-step sol–gel method followed by various sintering temperature was studied. The synthesized samples were first characterized by performing x-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) measurements. A linear dependence of the saturation magnetization with the YIG content in the samples was observed that the saturation magnetization increases from 4.18 to 20.2 emu/g when the YIG crystal content is increased from 43 % to 88 %. Then, the EMW absorbing performance were studied by measuring dielectric parameters of the samples in the X-band. The experimental results indicate that the higher sintering temperature reduce the intensity of Fe 2 O 3 peaks and enhance the formation of YIG chemical structure. Due to the both Fe 2 O 3 and YIG crystal phases, the Fe 2 O 3 /Y 3 Fe 5 O 12 interface enhances the EMW polarization and thus EMW absorbing performance. The minimum reflection loss was determined as −15.4 dB at 9.5 GHz frequency in YF1000 sample. The experimental results demonstrate that the sintering temperature has the prominent effect on the structural, magnetic and EMW absorbing properties of YIG. The results would be useful for the YIG-based microwave device applications. [ABSTRACT FROM AUTHOR]

Microwave materials with outstanding absorbing power and low cost are decisive for the electromagnetic issues in stealth technology. In the present work, Dy-Gd substituted YIG nano ferrites having Y 3−x-y Dy x Gd y Fe 5 O 12 ; (whereas x = 0.00, 0.025, 0.05, 0.075, 0.10; y = 0.00, 0.25, 0.50, 0.75, 1.00), were prepared by two-step sol-gel self-ignition route for absorption purpose. Rare earth cations such as Dy-Gd effects on the structural, and electromagnetic characteristics of YIG were evaluated. Different characterizations like XRD, FESEM, and VSM were used to evaluate the physicochemical and electromagnetic properties of the Dy-Gd co-doped YIG ferrites. A high-frequency vector network analyzer evaluated dielectric measurements such as real and imaginary permittivity and permeability, ac-conductivity, and dielectric loss of the Dy-Gd doped YIG ferrites. Dy-Gd doped YIG ferrites samples depicted single phase cubic garnet structure. Cation distributions of Dy-Gd doped YIG ferrites were also calculated. FESEM images revealed a homogeneous, closely packed grain size distribution of the Dy-Gd doped YIG samples. Magnetic properties such as saturation magnetization, remanence, coercivity, initial permeability, magnetic anisotropy constant, and Bohr magneton were also investigated using magnetic hysteresis loops and the SFD and high-frequency evaluations. Dielectric properties such as dielectric losses, ac conductivity, permeability, and permittivity of the Dy-Gd doped YIG samples show high values at x = 0.075 and y = 0.75. Metamaterial-based Dy-Gd doped YIG absorbers were designed and simulated in the CST software. The resonance peaks depicted the absorption at 3.6 GHz with absorptivity of 67 %, 75 %, and 85 % for x = 0.00- y = 0.00, x = 0.05-y = 0.5, and x = 0.075-y = 0.75, respectively. High saturation magnetization, low coercivity, and extraordinary dielectric absorption characteristics of Dy-Gd doped YIG ferrites make them appropriate for absorption, and EMI shielding applications in microwave regime. • Dy and In co-doped YIG (Y 3 Fe 5 O 12) nano-ferrites were prepared using sol gel self-ignition technique. • XRD, FTIR, SEM, VSM and VNA were used to evaluate the properties of YIG co-doped garnet ferrites. • Dy-In doped YIG nano-ferrites at x = 0.00- y = 0.00, x = 0.05-y = 0.5, and x = 0.075-y = 0.75 was simulated. • The resonance peaks depicted the absorption at 3.6 GHz with absorptivity of 67 %, 75 %, and 85 % respectively. • Dy-In doped YIG meta-absorber are suitable for absorption, and EMI shielding applications. [ABSTRACT FROM AUTHOR]

We investigated the magnetization dynamics through the magnetoimpedance effect in an integrated YIG/Pt-stripline system in the frequency range of 0.5 up to 2.0 GHz. Specifically, we explore the dependence of the dynamic magnetic behavior on the field orientation by analyzing beyond the traditional longitudinal magnetoimpedance effect of the transverse and perpendicular setups. We disclose here the strong dependence of the effective damping parameter on the field orientation, as well as verification of the very-low damping parameter values for the longitudinal and transverse configurations. We find considerable sensitivity results, bringing to light the facilities to integrate ferrimagnetic insulators in current and future technological applications.