Structure Of Yttrium Iron Garnet Research Articles

Synthesis and analysis of the magnetic properties of YIG by means of sol–gel and spark plasma sintering

We presented a study on the structure and magnetic properties of yttrium iron garnet (YIG), Y3Fe5O12, which was synthesized by means of sol–gel method and spark plasma sintering (SPS). The YIG nanoparticles were prepared by sol–gel method followed by 800 °C annealing for 3 h. SPS procedures with different temperatures (700 °C∼900 °C) and holding times (30 min ∼ 90 min) were performed to study the influence of SPS conditions on the structure and magnetic properties of YIG. The X-ray diffraction pattern and Raman spectrum confirmed the presence of YIG at all studied conditions. All samples were pure garnet phase except for the samples with too high temperatures (900 °C) and too long holding time (90 min). The impurities were inferred to be due to the hypoxic environment caused by the vacuum sintering condition of SPS. The magnetic properties of YIG samples were significantly affected by SPS conditions. The YIG sample became multi-domain at the temperature as low as 750 °C and grew to 89.1 nm at 850 °C for 30 min holding time benefiting from to the special sintering effect of SPS. Large particles with loose texture were formed by the formation of sintering neck between the adjacent particles when the SPS temperature was higher than 800 °C. It are confirmed that the sample with extended holding time at a moderate temperature (800℃/60 min) show the best soft-magnetic properties, whose Ms, Mr and Hc are 27.5 emu/g, 2.4 emu/g and 19.2 Oe respectively. The results show that this method has good potential in preparing YIG with good magnetic properties.

Effect of La3+ substitution on structural, microstructure, magnetic properties, and microwave absorbing ability of yttrium iron garnet

Synthesis and characterization of lanthanum-doped yttrium iron garnet (YIG) in the compositional series of Y(3-x)La(x)Fe5O12 (x = 0.0, 0.1, 0.3, and 0.5) were carried out. All compositions were made by using solid state reaction method with ball-milling technique. The phase formation, surface morphology, magnetic properties, and microwave absorbing ability of all compositions were characterized by using X-ray diffractometer, scanning electron microscope, vibrating sample magnetometer, and Vector network analyzer. The results reveal that all compositions are crystallized into Y3Fe5O12 phase (space group Ia-3d (230). It was observed that the lattice constant is increased from 1.2373 to 1.2421 nm with the increase of lanthanum substitution level from x = 0.0 to 0.5. The crystallite size of Y(3-x)La(x)Fe5O12 series calculated by Scherrer method is found to decrease from 78 nm in x = 0.0 to 63 nm in x = 0.5. The particle size distribution from the surface morphology image analysis is shifted to lower-range number with the increase of lanthanum substitution level from x = 0.0 to 0.5. The substitution process also affects the lattice distortion in La-doped samples and changes the bond angles and bond lengths of the YIG structure. As the results, a linear correlation between the Fe'–O–Fe bond angle with magnetic properties parameters of saturation magnetization (Ms) and remanence magnetization (Mr) was studied. Due to the lanthanum substitution process, all La3+-doped samples possess higher Ms and Mr values compared to the original composition. The results of Vector network analyzer show that the improvement of the Ms and Mr plays an important role in enhancing the microwave absorbing ability of the materials. The minimum RL changed from –8.22 dB (∼ 85.22% microwave absorption) in x = 0.0 to -14.21 dB (∼ 96.25% microwave absorption) in x = 0.5. The enhancement mainly ascribed to the natural magnetic resonance loss and dipole-polarization loss due to the substitution process. The decreasing particle size also enhanced the microwave absorbing ability of the La-doped samples via multiple-reflections mechanism.

Tuning of Magnetic Damping in Y3Fe5O12/Metal Bilayers for Spin-Wave Conduit Termination.

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.

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&gt;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&amp;gt;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.

Spin transport properties of Bi&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;3–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;12 &lt;/sub&gt;thin films prepared by spin coating

Yttrium iron garnet (YIG), as a room temperature ferrimagnetic insulator with low damping and narrow ferromagnetic resonance linewidth, has been the research hotspot in spintronics because of its spin transport properties. Bi is one of the most common doping elements used in YIG, and some researches have proved that it can tune the magnetic properties of YIG. Previous studies of Bi&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;3–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; thin films focused on the evolutions of their structures, morphologies, and magnetic characteristics. Yet, the effects of Bi&lt;sup&gt;3+&lt;/sup&gt; substitution of Y&lt;sup&gt;3+&lt;/sup&gt; on spin transport in YIG thin films have not been systematically studied. The regulation of YIG spin transport by doping is expected to provide a new idea for the spintronics exploration of Pt/YIG system. In this work, we prepare a series of Bi&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;3–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; films with different doping ratios by spin coating. And we investigate the effects of Bi&lt;sup&gt;3+&lt;/sup&gt; on morphology, structure and spin transport properties of YIG films. The results show that Bi doping does not change the crystal structure of YIG. The absorption of the film increases and the bandgap decreases with the increase of doping ratio. The X-ray photoelectron spectroscopy (XPS) indicates the co-existence of Bi&lt;sup&gt;3+&lt;/sup&gt; and Bi&lt;sup&gt;2+&lt;/sup&gt;. The regulation of Bi doping on spin transport is reflected in the fact that the magnon diffusion length of Bi&lt;i&gt;&lt;sub&gt;x&lt;/sub&gt;&lt;/i&gt;Y&lt;sub&gt;3–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; films is significantly smaller than that of pure YIG films. Meanwhile, we find that the obvious spin Hall magnetoresistance can still be detected in the Pt/Bi&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Y&lt;sub&gt;3–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Fe&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; heterostructure, and the amplitude is the largest when &lt;i&gt;x&lt;/i&gt; = 0.3.

Влияние амплитуды СВЧ-воздействия на спиновый ток границы платина/железоиттриевый гранат

A numerical study of the features of the propagation of spin waves in a waveguide made of yttrium iron garnet (YIG) and Fe-Rh alloy in the form of a plate, located on top of the central part of the YIG, is carried out. Based on the simulation results, the possibilities of controlling the dynamics of spin waves in the structure under study were also revealed. Micromagnetic numerical simulation was used to study the transfer of a spin-wave signal in a multimode mode by numerically solving the Landau – Lifshitz – Hilbert equation. Transformation of the transmission spectra of spin waves shows that the proposed structure will make it possible to control the propagation of spin-wave modes due to a sharp change in the Fe-Rh magnetization in the region of the magnetic phase transition temperature close to room temperature. In addition, the spin wave signal can be controlled by a small temperature change in the Fe-Rh plate generated by the laser radiation. The two-layer structure of YIG / Fe-Rh, from an applied point of view, can be used as a functional unit in planar magnon networks performing space-frequency demultiplexing and filtering of spin-wave modes.

Torsional modes in the magnetoelectric effect for a two-layer ferrimagnet-piezoelectric YIG / GaAs structure

The article is devoted to the theoretical study of the magnetoelectric (ME) effect in the magnetostrictive-piezosemiconductor structure of yttrium iron garnet (YIG) - gallium arsenide (GaAs) in the torsional mode. Earlier, it was found that the ME effect significantly increases with the transition from the low-frequency range to the region of electromechanical resonance (EMR). There are known results on the study of the ME effect in the range of different EMR modes: planar, flexural, and shear. This article proposes to consider the ME effect in the torsional mode region in a layered YIG-GaAs composite. Interest in this phenomenon is associated both with the study of the newest effect, and with the possibility of studying the ME effect in the region of magnetoacoustic resonance, i.e. when the torsional mode coincides with the spin wave in the region of ferromagnetic resonance. The results obtained can find application in the design of new ME devices.

Preferential site occupancy of Ni ions and oxidation state of Fe ions in the YIG crystal structure obtained by sol-gel method

In this work, we present a study about the preferential site occupancy of Ni ions and the oxidation state of Fe ions in the yttrium iron garnet (YIG) crystal structure of nanoparticles obtained by sol-gel method. Transmission electron microscopy (TEM) showed particles and clusters with irregular shapes. Selected area electron diffraction (SAED) showed bright spots and diffuse rings characteristic of well-defined crystals supporting the presence of fine particles. The distribution of Ni and Fe ions in the tetrahedral (d) and octahedral (a) sites of YIG structure has been revealed by the Mössbauer spectroscopy. The Electron paramagnetic resonance (EPR) results confirmed the inclusion of Ni in the Fe sites and an increase in the g factor for the doped YIG sample. X-ray Photoelectron Spectroscopy (XPS) has been employed to check the valence states, confirming that Y, Ni and Fe are predominantly in the Y3+, Ni2+, Fe3+ and Fe2+ oxidation states. This paper contributes to the understanding of preferential site occupancy of Ni in the yttrium iron garnet; a compound with few studies and high importance in spintronics applications.

The role of Dy incorporation in the magnetic behavior and structural characterization of synthetic Ce, Bi-substituted yttrium iron garnet

In this Study, the effects of substitution of Y3+ by Dy3+ ions on the crystal structure and magnetic properties for Y2.8-xDyxCe0.10Bi0.10Fe5O12 (x = 0.0, 0.2, 0.4, 0.6) and pure yttrium iron garnet (YIG) produced by conventional method have been investigated. The Fe2O3, Y2O3, CeO2 and Dy2O3 powders were mixed in stoichiometric ratio and annealed at different temperatures from 1000 to 1420 °C in air atmosphere. At the final stage, Bi2O3 was aggraded in the YIG and annealed in 1000 °C in an air atmosphere. The phase structure, morphology and magnetic properties were investigated using Raman Spectroscopy (RS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscope (SEM) and Vibrating Sample Magnetometer (VSM), respectively. The X-ray diffraction data showed a nearly pure and single-phase of doped garnet with small amounts of CeO2 secondary phase. The RS result reveals the characteristic peak of the YIG structure. The XPS analysis indicates that bismuth, dysprosium, yttrium and iron ions exist in their corresponding “+3” valence states whereas cerium finds in “+3” and “+4”. The saturation magnetization augments from 33.47 emu/g for pure YIG to 35.15 emu/g for xDy = 0.2 due to the small increase in d-p wave function overlap between the octahedral Fe3+ ion and intervening oxygen ion. The coercivity values decrease from 20.16 Oe for pure YIG to 17.78 Oe for xDy = 0.6. The improved magnetic properties promote the doped garnets to microwave absorption and sensing applications.

Crystal structure and magnetic properties of cerium-doped YIG: Effect of doping concentration and annealing temperature

We present a study of the effect of the substitution of Y3+ by Ce3+ on the crystal structure and magnetic properties of cerium-doped yttrium iron garnet (YIG), CexY3-xFe5O12 (0 ≤ x ≤ 0.5), which was synthesized using high-energy ball milling. In particular, we aimed to study the effect of the cerium concentration and the annealing temperature on the crystal structure and magnetic properties of the Ce-doped YIG. Fe2O3, Y2O3, and Ce2(CO3)3 were mixed in a stoichiometric ratio, milled for 5 h, and annealed at different temperatures, from 1000 to 1400 °C. The X-ray diffraction pattern confirmed the presence of CeO2 as a secondary phase, together with the formation of the YIG structure, at all studied temperatures and compositions. A complete solid solution of Ce3+ in the garnet structure was obtained for the samples annealed at 1400 °C. Increasing the Ce3+ content resulted in a consistent decrease in the saturation magnetization and a slight decrease in the coercivity, resulting from the insertion of Ce3+ into the YIG structure and the presence of CeO2 as a secondary phase.

The synthesis of single-phase yttrium iron garnet doped zinc and some structural and magnetic properties

This work presents the single phase formation of yttrium iron garnet (YIG) doped with divalent Zn ions in samples fabricated by the sol–gel method and heat treated at 900 °C. We used stoichiometric amounts according to the formula Y3(Fe1−xZnx)5O12, (x = 0, 0.01, 0.03 and 0.05). The x-ray diffraction data show the single phase formation with the lattice parameter increasing with the Zn concentration. The scanning electron microscopy images showed nanoparticles with a rod format, crowding more as the doping increased. Energy dispersive x-ray spectroscopy results confirmed the presence of Zn in the YIG structure. The Raman spectroscopy measurements show characteristic peaks of the YIG structure, and some characteristic peaks increasing with the Zn concentration. This confirms our successful result doping the YIG structure with the divalent Zn ion replacing the Fe positions. Magnetic measurements show coercive field values dominated by the shape and agglomeration of nanoparticles. For low doping we have a value of 88.50 Oe attributed to the particles’ morphology, and for the highest Zn concentrations the effects of agglomeration diminish the coercivity to 50 Oe. The total magnetic moment for low Zn concentrations increases slightly due to the replacement of Fe by Zn. For higher Zn concentrations, we can see a diminution of the magnetic saturation which is due to the growth of the crystal lattice parameter and thus a weakening of the exchange interactions between the magnetic sub-lattices in the Y3(Fe1−xZnx)5O12 ferrimagnetic compound. Changes in the magnetic moment do not have large values, showing the possibility of doping without a drastic change in this quantity.

Structure and Magnetic Properties of Ce-Substituted Yttrium Iron Garnet Prepared by Conventional Sintering Techniques

Y3−xCexFe5O12 (CeYIG) ceramics, with x = 0, 0.15, 0.25, 0.35, 0.45, and 0.5, were fabricated by a conventional ceramic sintering technique. We studied the structures and magnetic fields of a series of CeYIG ceramics using X-ray powder diffraction, a scanning electron microscope, and a superconducting quantum interference device magnetometer. Findings showed that the substitution limit of the concentration of Ce3+ ions in the yttrium iron garnet structure was approximately x = 0.25. An extra CeO2 phase was detected in the ceramic when the addition of CeO2 content overtook the limit. The lattice constants and relative densities increased by increasing the Ce3+ contents in the ceramics. First, the saturation magnetization increased gradually with increases in the substitute concentration of Ce3+ ions and then decreased gradually when x = 0.35, 0.45, and 0.5. Overall, this study showed that the Y3−xCexFe5O12 material with x ≤ 0.15 exhibited excellent magnetic properties. Hence, the material show promise for magneto-optical and microwave communication applications.

Sintering and grain growth control of high dense YIG

The densification and grain growth of yttrium iron garnet (YIG) were systematically studied to produce highly densified YIG via conventional solid-state route (CSSR). The percentage of purity and structure of YIG was confirmed by XRD characterization. SEM micrographs revealed that with increasing sintering temperature and time, the grain size and the average pores radius (Rp) increased, while the number of pores per volumes (Nv) decreased. The maximum material density obtained using Archimedes principle was 97.9% of that of theoretical density (ρtheory). It required approximately 132.55kJ/mol of energy to produce dense YIG sintered for 6h at 1420°C. However, beyond this temperature, a new phase that confirmed the presence of YFe2O4-δ phase was found through EDX analysis along the grain boundaries. This occurrence lowered the grain boundary mobility thereby resulting in slight change in density. Therefore, the results suggested that a highly densified YIG (ρtheory of ≈98%) could be successfully obtained when YIG is sintered at 1420°C for 6h.

Indium-substitution and indium-less case effects on structural and magnetic properties of yttrium-iron garnet

The effect of indium (In) substitution in the dynamics of structure and ferrimagnetism of yttrium iron garnet (YIG) employing sintering temperature as a temporary agent of composition and structural changes was reported in this study. The nanoparticles of YIG powder samples with various In content (x=0.0–0.4) were prepared via the mechanical alloying (MA) technique. A brief, yet revealing characterization of the samples was carried out via transmission electron microscope, X-ray diffraction, Raman spectroscopy, B–H Hysteresisgraph, and LCR-metre. The X-ray diffraction analysis of the samples prepared via the MA indicates the formation of single phase YIG structure at much lower sintering temperature than that in the conventional ceramic technique. The lattice constant increases as In content increases which obeys Vegard's Law due to the larger In3+ ions replacing the smaller Fe3+ ions. The saturation induction increased reaching about 699.1G for x=0.3 and decreased with further In substitution. Three stages of ordered magnetism formation were identified which attributed to development of crystallinity and larger grains for magnetic domain accommodation. The Curie temperature shows a decrement in their values with In content due to weakening of superexchange interactions. Raman shifts from 268.1 to 272.2cm−1 with increasing In content were observed due to stress developed in the YIG crystal structure.

Influence of indium substitution and microstructure changes on the magnetic properties evolution of Y3Fe5−xInxO12 (x = 0.0–0.4)

The role of indium (In) substitution in the dynamics of ferrimagnetism, structure and microstructure of yttrium iron garnet (YIG) employing sintering temperature as a temporary agent of composition and microstructural changes was examined closely and reported in this study. The nanoparticles of YIG powder samples with various In content (x = 0.0, 0.1, 0.2, 0.3, 0.4) were prepared via the mechanical alloying (MA) technique. A brief, yet revealing characterization of the samples was carried out by using a transmission electron microscopy, X-ray diffraction, Raman spectroscopy and scanning electron microscopy to analyse the structural and morphological properties, whereas B–H hysteresis graph and LCR-meter were used to measure the magnetic and thermo-magnetic behaviour respectively. The X-ray diffraction analysis of the samples prepared via the MA indicates the formation of single phase YIG structure at much lower sintering temperature than that in the conventional ceramic technique. The lattice constant increases as In content increases which obeys Vegard’s law due to the larger In3+ ions replacing the smaller Fe3+ ions. The grain size also increased with In content, indicating that the In3+ ion acts as a grain growth promoter. The saturation induction increased reaching about 699.1 G for x = 0.3 and decreased with further In substitution. Three stages of ordered magnetism formation were identified which attributed to development of crystallinity and larger grains for magnetic domain accommodation. The Curie temperature shows a decrement of 60 °C for In content changes from x = 0.0 to x = 0.4 due to weakening of superexchange interactions. Raman shifts from 268.1 to 272.2 cm−1 with increasing In content were observed due to stress developed in the YIG crystal structure. Possible mechanisms contribute to these properties are discussed in this paper.

New EM Transmitter with Y&lt;sub&gt;3&lt;/sub&gt;Fe&lt;sub&gt;5&lt;/sub&gt;O&lt;sub&gt;12&lt;/sub&gt; Based Magnetic Feeders Potentially Used for Seabed Logging Application

Sea bed logging (SBL) is a new technique for detection of deep target hydrocarbon reservoir. Powerful electromagnetic (EM) transmitter is required for the transmission of EM signal underneath the seabed. New aluminum transmitter with yttrium iron garnet (Y3Fe5O12) based magnetic feeders was used in a scale tank to increase the magnitude of the magnetic field. Yttrium iron garnet samples were prepared using self combustion technique at different sintering temperatures of 750°C, 950°C and 1150°C. Characterizations of Y3Fe5O12 samples were done by using XRD, RAMAN, FESEM and Impedence network analyser. X-ray diffraction results revealed that yttrium iron garnet phase with good crystallinity appeared at sintering temperature of 1150°C. Nanoparticles size ranging from 60 to 110 nm was investigated. Raman results also confirmed garnet structure of yttrium iron garnet at sintering temperature of 1150°C. Field emission scanning electron microscopy (FESEM) was used to image the morphology of the Y3Fe5O12 nanoparticles. Magnetic properties of Y3Fe5O12 magnetic feeders illustrates that Y3Fe5O12 has high Initial permeability (58.054), high Q-factor (59.842) and low loss factor (0.0003) at sintering temperature of 1150°C. Y3Fe5O12 magnetic feeders with high Q factor were chosen for new aluminum EM transmitter. Experiments with a scale factor of 2000 were carried out in scaled tank. It was found that Al transmitter with Y3Fe5O12 magnetic feeders increased magnitude of magnetic field strength up to 180%.

Mössbauer study of Al and Cr co-substituted Yttrium iron garnets

The Mossbauer spectra of Y3Al x Cr X Fe5 − 2x O12 (x = 0.0 to 0.6) measured at 300 K have been fitted with two sextets in the ferrimagnetic state corresponding to Fe3+ at the octahedral (a) and the tetrahedral (d) sites for x ≤ 0.6. The isomer shifts (δ) and quadrupole splitting (ΔEQ) indicate the presence of high spin Fe3+ ions in the tetrahedral (d) and octahedral (a) sites, typical of yttrium of yttrium iron garnet structure. Mossbauer results have shown that Al3+, enters a-sites only but Cr3+ enters both a-and d-sites.

Dynamics of a collinear two-position multisublattice ferrimagnet in a three-sublattice model as applied to yttrium iron garnet

Results of investigations of magnetoelectric effects in substances with a ferrimagnetic ordering are reported. The consideration is performed on the example of yttrium iron garnet (YIG) belonging to the space group Oh10. In the unit cell of the crystal structure of YIG, the magnetic Fe ions occupy 16 positions of the a type and 24 positions of the d type. It is shown that the magnetoelectric effects in YIG can be described in the model of three (rather than 20) magnetic sublattices, namely Ma, Md1 and Md2. The magnetization vector Ma is determined by Fe ions located in a positions. The Fe ions in d positions are located in two sublattices (d1 and d2) related by a symmetry center. In such a three-sublattice model of a two-position ferrimagnet, one more branch (antimagnon) appears in the spectrum apart from two ferromagnon branches. The third branch is caused by vibrations of only antiferromagnetism vector L = Md1 − Md2. This branch is associated with changes in the dielectric permittivity and refraction index of the ferrimagnetic medium that are responsible for the magnetoelectric effects.

Temperature dependence of satellite structure of yttrium iron garnet containing Y 3+(a) defects and Al 3+(d) substitutions: experiment and model

NMR spectra on 57Fe nuclei in yttrium iron garnet (YIG) containing Y 3+(a) defects and Al 3+(d) substitutions were measured in the temperature range 4.2–360 K in zero external magnetic field. The temperature dependencies of satellite lines caused by Y 3+(a), Al 3+(d) impurities were determined. Theoretical description of the temperature behavior of the main and satellite lines has been carried out in the frame of model based on the Bethe–Peierls–Weiss approximation.