Nowadays the yttrium iron garnet(Y3Fe5O12, YIG) films are widely used in the microwave and spin wave devices due to their low damping constant and long propagation distance for spin waves. However, the performances, e...Nowadays the yttrium iron garnet(Y3Fe5O12, YIG) films are widely used in the microwave and spin wave devices due to their low damping constant and long propagation distance for spin waves. However, the performances, especially the frequency stability, are seriously affected by the relaxation of the interface magnetic moments. In this study, the effect of out-of-plane magnetization depinning on the resonance frequency shift(△ fr) was investigated for 3-μm YIG films grown on Gd3Ga5O12(GGG)(111) substrates by liquid-phase epitaxy. It is revealed that the ferromagnetic resonance(FMR) and spin wave propagation exhibit a very slow relaxation with relaxation time τ even longer than one hour under an out-of-plane external magnetic bias field. The △ fr span of 15.15–24.70 MHz is observed in out-of-plane FMR and forward volume spin waves. Moreover, the △ fr and τ depend on the magnetic field. The △ fr can be attributed to that the magnetic moments break away from the pinning layer at the YIG/GGG interface. The thickness of the pinning layer is estimated to be about9.48 nm to 15.46 nm according to the frequency shifting. These results indicate that △ fr caused by the pinning layer should be addressed in the design of microwave and spin wave devices, especially in the transverse magnetic components.展开更多
Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal struct...Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDS) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.展开更多
Yttrium iron garnet, Y3Fe5O12 (YIG) powders were synthesized by mechanochemical processing (MCP) from different iron sources (FeO, Fe2O3 and Fe3O4) mixed with Y2O3, followed by a heat treatment. The aim of this work i...Yttrium iron garnet, Y3Fe5O12 (YIG) powders were synthesized by mechanochemical processing (MCP) from different iron sources (FeO, Fe2O3 and Fe3O4) mixed with Y2O3, followed by a heat treatment. The aim of this work is to demonstrate that MCP followed by annealing at very low temperatures (as compared with the classic solid state reaction) can induce the formation of nanostructured YIG. The effect of iron source on final structure was also studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the synthesized powders. The precursors mixed in a stoichiometric ratio to obtain YIG were milled at room temperature in a shaker mixer mill with a ball:powder weight ratio of 10:1. A partial synthesis of YIG was achieved after 9 h of milling time by using the three sources of iron;however, a significant fraction of the product was the perovskite YFeO3. The largest yield of YIG was obtained by using FeO. In all cases a single garnet phase could only be completely obtained after an annealing process at 900?C, around 400?C lower than the typical temperatures to prepare the material by solid state reaction. An analysis of the microstrain and lattice parameters associated with peak displacements is discussed.展开更多
The Ca-Sn co-substituted yttrium iron garnet(YIG)ferrite materials were prepared by the traditional oxide solid-state reaction method,and the influence of forming pressure on the density,morphology and magnetic proper...The Ca-Sn co-substituted yttrium iron garnet(YIG)ferrite materials were prepared by the traditional oxide solid-state reaction method,and the influence of forming pressure on the density,morphology and magnetic properties of YIG ferrite was systematically studied.The results show that the density of YIG ferrite green body increases with the increase of the forming pressure,while the density of its sintered body shows a trend of first increasing and then decreasing.At the same time,the ferromagnetic resonance(FMR)linewidth of YIG sample first decreases and then increases.Meanwhile,the effects of forming pressure on the saturation magnetization,remanence and coercivity of the sample can be ignored.This study proves that the density and FMR linewidth of YIG materials can be controlled by regulating the forming pressure and the best performance is obtained for the sample prepared under a forming pressure of 5 MPa.展开更多
基金National Natural Science Foundation of China(Grant Nos.11674187 and 51871127)Technology on Electronic Test&Measurement Laboratory(Grant No.6142001180103).
文摘Nowadays the yttrium iron garnet(Y3Fe5O12, YIG) films are widely used in the microwave and spin wave devices due to their low damping constant and long propagation distance for spin waves. However, the performances, especially the frequency stability, are seriously affected by the relaxation of the interface magnetic moments. In this study, the effect of out-of-plane magnetization depinning on the resonance frequency shift(△ fr) was investigated for 3-μm YIG films grown on Gd3Ga5O12(GGG)(111) substrates by liquid-phase epitaxy. It is revealed that the ferromagnetic resonance(FMR) and spin wave propagation exhibit a very slow relaxation with relaxation time τ even longer than one hour under an out-of-plane external magnetic bias field. The △ fr span of 15.15–24.70 MHz is observed in out-of-plane FMR and forward volume spin waves. Moreover, the △ fr and τ depend on the magnetic field. The △ fr can be attributed to that the magnetic moments break away from the pinning layer at the YIG/GGG interface. The thickness of the pinning layer is estimated to be about9.48 nm to 15.46 nm according to the frequency shifting. These results indicate that △ fr caused by the pinning layer should be addressed in the design of microwave and spin wave devices, especially in the transverse magnetic components.
基金The authors are grateful to the Brazilian Agencies:Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior(CAPES),Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq),(CNPq N 4/2021-Bolsa de Produtividade em Pesquisa-PQ 307659/2021-6),(Chamada CNPq/MCTI/FNDCT N°18/2021-Faixa A,407796/2021-5)Financiadora de Estudos e Projetos(FINEP)and Fundacao de Amparo a Ciencia e Tecnologia de Pernambuco(FACEPE)(APQ-0635-3.03/21-Jovens Pesquisadores).
文摘Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDS) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.
文摘Yttrium iron garnet, Y3Fe5O12 (YIG) powders were synthesized by mechanochemical processing (MCP) from different iron sources (FeO, Fe2O3 and Fe3O4) mixed with Y2O3, followed by a heat treatment. The aim of this work is to demonstrate that MCP followed by annealing at very low temperatures (as compared with the classic solid state reaction) can induce the formation of nanostructured YIG. The effect of iron source on final structure was also studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the synthesized powders. The precursors mixed in a stoichiometric ratio to obtain YIG were milled at room temperature in a shaker mixer mill with a ball:powder weight ratio of 10:1. A partial synthesis of YIG was achieved after 9 h of milling time by using the three sources of iron;however, a significant fraction of the product was the perovskite YFeO3. The largest yield of YIG was obtained by using FeO. In all cases a single garnet phase could only be completely obtained after an annealing process at 900?C, around 400?C lower than the typical temperatures to prepare the material by solid state reaction. An analysis of the microstrain and lattice parameters associated with peak displacements is discussed.
文摘The Ca-Sn co-substituted yttrium iron garnet(YIG)ferrite materials were prepared by the traditional oxide solid-state reaction method,and the influence of forming pressure on the density,morphology and magnetic properties of YIG ferrite was systematically studied.The results show that the density of YIG ferrite green body increases with the increase of the forming pressure,while the density of its sintered body shows a trend of first increasing and then decreasing.At the same time,the ferromagnetic resonance(FMR)linewidth of YIG sample first decreases and then increases.Meanwhile,the effects of forming pressure on the saturation magnetization,remanence and coercivity of the sample can be ignored.This study proves that the density and FMR linewidth of YIG materials can be controlled by regulating the forming pressure and the best performance is obtained for the sample prepared under a forming pressure of 5 MPa.
