Magnetic bubbles have again become a subject of significant attention following the experimental observation of topologically nontrivial magnetic skyrmions. In recent work, tailoring the shape of the bubbles is consid...Magnetic bubbles have again become a subject of significant attention following the experimental observation of topologically nontrivial magnetic skyrmions. In recent work, tailoring the shape of the bubbles is considered a key factor for their dynamics in spintronic devices. In addition to the reported circular, elliptical, and square bubbles, here we observe triangular bubble domains in bismuth-doped yttrium iron garnet(Bi-YIG) using Kerr microscopy. The bubble domains evolve from discrete circular to latticed triangular and hexagonal shapes. Further, the orientation of the triangular bubbles in the hexagonal lattices can be flipped by decreasing the magnetic field. The sixfold in-plane magnetic anisotropy of Bi-YIG(111) crystal, which is presumably the mechanism underlying the triangular shape of the bubbles, is measured as1179 erg/cm~3. The study of the morphologies of topologically trivial bubbles in YIG offers insight into nontrivial spin textures, which is appealing for future spintronic applications.展开更多
Cerium-substituted yttrium iron garnet(Ce x Y 3-xFe 5O 12, Ce∶YIG) was prepared via coprecipitation. The structu re, morphology, valence state and constituent of Ce ions were investigated respe ctively. X-ra...Cerium-substituted yttrium iron garnet(Ce x Y 3-xFe 5O 12, Ce∶YIG) was prepared via coprecipitation. The structu re, morphology, valence state and constituent of Ce ions were investigated respe ctively. X-ray powder diffraction(XRD) analysis shows that Ce∶YIG was of singl e cubic YIG phase. The result of X-ray photoelectron spectroscopy(XPS) indicate s the Ce ions in Ce∶YIG were in the state of trivalence. Scanning electron micr oscope(SEM) demonstrates the conglobation of Ce∶YIG particles about 0.2μm scal e.The magnetic properties were studied by a vibrating sample magnetometer(VSM) a nd the result exhibits that substitution of Ce 3+ changes the magnetic para meters of YIG. The effects of doping content of Ce ions and synthesis temperatu re on valence control were discussed in detail.展开更多
The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber link...The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber links the sensor head to the source and detection system, in which the technique of phase shift cancellation is used to cancel the phase shift that accumulatein the optical fiber. Flux concentrators were exploited to enhance the YIG crystal magneto-optic sensitivity .The sensor system exhibited a noise-equivalent field of 8 pT/√Hz and a 3 dB bandwidth of ～10 MHz.展开更多
Magneto-electric properties of the magnetic domains local areas of bismuth-substituted yttrium iron garnet films are investigated. The electromagneto-optical (EMO) scanning method was used in our experiments when prob...Magneto-electric properties of the magnetic domains local areas of bismuth-substituted yttrium iron garnet films are investigated. The electromagneto-optical (EMO) scanning method was used in our experiments when probing by laser beam various sites of separate magnetic domains of the film. Registered in our experiments the nonlinear and linear components of EMO effect does not remain to constants at optical scanning of various points of the magnetic domain. I.e. the local EMOE picture from the separate sites of the domain must be more informative than an averaged one in the multidomain case.展开更多
Y_(3)Fe_(5)O_(12)(YIG)crystals are highly desirable for the fabrication of mid-infrared isolators with the rapid growth of optical communications,although it is rather challenging to grow large size and high-quality s...Y_(3)Fe_(5)O_(12)(YIG)crystals are highly desirable for the fabrication of mid-infrared isolators with the rapid growth of optical communications,although it is rather challenging to grow large size and high-quality single crystals.Dy^(3+)doping is expected to improve the optical and magneto-optical prope rties.However,high quality Dy:YIG crystals and the adjustment of Dy^(3+)on the structure and optical behavior of YIG crystal remain unclear,impeding its practical applications.Herein,a series of Y_(3-x)Dy_(x)Fe_(5)O_(12)(x=0,0.5,1.0,1.5,3)solid solution crystals was grown by the flux-Bridgman method and single crystals up to 25 mm were obtained.With the introduction of Dy^(3+),lattice parameters are gradually enlarged from 1.2379 nm(YIG)to 1.2420 nm(DyIG).Typical Dy^(3+)absorption peaks are observed around 1070,1265 and 1670 nm.The refractive index decreases from 2.37(500 nm)to 2.10(2500 nm)for YIG crystal,and it reduces from 2.47(500 nm)to 2.16(2500 nm)for DyIG crystal.The optical bandgaps remain almost unchanged for Dy:YIG crystals.The optical dispersion of the refractive indices was finely fitted by the Wemple and DiDomenico(WDD)and the Sellmeier models,respectively.With the increase of Dy^(3+)content,the saturation magnetization(Ms)decreases significantly from 23.62 emu/g(YIG)to 5.33 emu/g(DyIG).Small coercive field is persisted for this system,endowing small external magnetic field.These results provide valuable references for the manipulation of rare earths on the properties of magnetooptical crystals,which is beneficial to the design of high-performance garnet crystals for the application of optical switching and non-reciprocal related devices.展开更多
Synthesis and characterization of lanthanum-doped yttrium iro n garnet(YIG)in the compositional se ries of Y_(3-x)La_(x)Fe_(5)O_(12)(x=0.0,0.1,0.3,and 0.5)were carried out.All compositions were made by using solid sta...Synthesis and characterization of lanthanum-doped yttrium iro n garnet(YIG)in the compositional se ries of Y_(3-x)La_(x)Fe_(5)O_(12)(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 an X-ray diffractometer,a scanning electron microscope,a vibrating sample magnetometer,and a Vector network analyzer.The results reveal that all compositions are crystallized into Y_(3)Fe_(5)O_(12)phase(space group la-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=0.0-0.5.The crystallite size of Y_(3-x)La_(x)Fe_(5)O_(12)series calculated by Scherrer method is found to decrease from 78 nm in x=0.0-63 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(M_(s))and remanence magnetization(M_(r))was studied.Due to the lanthanum substitution process,all La^(3+)-doped samples possess higher M_(s)and M_(r)values compared to the original composition.The results of Vector network analyzer show that the improvement of the M_(s)and M_(r)plays an important role in enhancing the microwave absorbing ability of the materials.The minimum RL changes 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 is mainly ascribed to the natural magnetic resonance loss and dipoIe-polarization loss due to the substitution process.The decreasing particle size also enhances the microwave absorbing ability of the La-doped samples via multiple-reflections mechanism.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
A comprehensive study of the magnetic properties of Y3-2xCa2xFe5-xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates th...A comprehensive study of the magnetic properties of Y3-2xCa2xFe5-xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates the formation of single cubic phase. Vibrating sample magnetometry (VSM) and a superconducting quantum-interference device (SQUID) were used to measure the magnetic properties, especially the magnetization and thermo-magnetic behavior. The magnetization curves exhibit the typical characteristics of ferrimagnetic materials at both 4.2 K and at room temperature. The samples have a low coercivities (between 20 and 40 Oe) and saturation magnetizations as high as 36 emu/g at 4.2 K. The saturation magnetization decreases with V and Ca contents, reaching about 8 emu/g at 4.2 K (x = 1). For all samples, the saturation magnetization decreases with increasing temperature, whereas the Curie temperature increases for small values of x, from 557 K for x = 0 to a maximum of 590 K for x = 0.2. For larger values of x, it decreases and reaches 525 K for x = 1.0. The basic experimental trends reflect the occupancy of the tetrahedral 24d sites by vanadium in combination with the predominant intersublattice exchange constant Jad, although the nonzero magnetization at x = 1.0 indicates that about 10% of the substituted V atoms goes onto the octahedral 16a sites.展开更多
Y_(3)Fe_(5)O_(12)(YIG) and Bi Y_(3)Fe_(5)O_(12)(Bi:YIG) films were epitaxially grown on a series of(111)-oriented garnet substrates using pulsed laser deposition. Structural and ferromagnetic resonance characterizatio...Y_(3)Fe_(5)O_(12)(YIG) and Bi Y_(3)Fe_(5)O_(12)(Bi:YIG) films were epitaxially grown on a series of(111)-oriented garnet substrates using pulsed laser deposition. Structural and ferromagnetic resonance characterizations demonstrated the high epitaxial quality, extremely low magnetic loss and coherent strain state in these films. Using these epitaxial films as model systems, we systematically investigated the evolution of magnetic anisotropy(MA) with epitaxial strain and chemical doping. For both the YIG and Bi:YIG films, the compressive strain tends to align the magnetic moment in the film plane while the tensile strain can compete with the demagnetization effect and stabilize perpendicular MA. We found that the strain-induced lattice elongation/compression along the out-of-plane [111] axis is the key parameter that determines the MA. More importantly, the strain-induced tunability of MA can be enhanced significantly by Bi doping;meanwhile, the ultralow damping feature persists. We clarified that the cooperation between strain and chemical doping could realize an effective control of MA in garnet-type ferrites, which is essential for spintronic applications.展开更多
钇铁石榴石(yttrium iron garnet,YIG)的自旋输运特性一直是自旋电子学的研究重点之一.Bi作为YIG最常见的掺杂元素,其薄膜Bi_(x)Y_(3-x)Fe_(5)O_(12)的磁光特性已经被广泛研究.但Bi^(3+)取代Y^(3+)对YIG自旋输运的影响规律还没有被系统...钇铁石榴石(yttrium iron garnet,YIG)的自旋输运特性一直是自旋电子学的研究重点之一.Bi作为YIG最常见的掺杂元素,其薄膜Bi_(x)Y_(3-x)Fe_(5)O_(12)的磁光特性已经被广泛研究.但Bi^(3+)取代Y^(3+)对YIG自旋输运的影响规律还没有被系统地研究过.本文利用溶液旋涂法制备了不同掺杂比的Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜,并研究Bi掺杂对YIG薄膜形貌结构和自旋输运性能的影响.结果表明Bi掺杂没有改变YIG的晶体结构,掺杂比上升令薄膜的吸收强度增大,带隙减小.XPS表明了Bi^(3+)和Bi^(2+)的存在.Bi掺杂在自旋输运上的调控体现在Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜的磁振子扩散长度相比纯YIG薄膜有所减小.同时研究发现Pt/Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜中依然可以检测到明显的自旋霍尔磁电阻,并在x=0.3时振幅最大.展开更多
In this work,we present a new and fast method to obtain the single phase YFeO(YIG,cubic) and YFeO(YIP, orthorhombic) nanocrystals based on hydrothermal technique. The influence of initial Y/Fe mole ratio and calcinati...In this work,we present a new and fast method to obtain the single phase YFeO(YIG,cubic) and YFeO(YIP, orthorhombic) nanocrystals based on hydrothermal technique. The influence of initial Y/Fe mole ratio and calcination temperature on the nature, purity, phase structure, and morphology of the product was investigated by X-ray diffraction(XRD), Fourier-transform infrared(FT-IR) spectroscopy,energy-dispersive(EDX) X-ray spectroscopy, and field emission scanning electron microscopy(FESEM).The results show that the transformation of the as-synthesized YIG from amorphous to orthorhombic and finally to cubic phase occurs with the increase of annealing temperature. On this basis, the pure cubic phase YIG can be obtained by calcination(at 1100℃) of the precursor which is prepared using the hydrothermal treatment of mole ratio of Y:Fe = 1:1.5 exposure to an ammonia atmosphere. Also, the initial Y/Fe mole ratio of 1:1 and calcination temperature of 1000 ℃ are the optimal conditions to form single-phase nanocrystalline YIP. Further, vibrating sample magnetometry(VSM) measurements illustrate the average magnetic saturation, coercivity and remanence of 2.73 and 15.00 emu/g, 42.74 and40.02 Oe, and 1.65 and 4.30 emu/g for YIP and YIG nanocrystals, revealing their soft ferromagnetic character.展开更多
基金support by the National Natural Science Foundation of China (Grant Nos. 52061135105 and 12074025)support by the National Natural Science Foundation of China (Grant Nos. 11974079, 12274083, and 12221004)the Shanghai Municipal Science and Technology Basic Research Project (Grant No. 22JC1400200)。
文摘Magnetic bubbles have again become a subject of significant attention following the experimental observation of topologically nontrivial magnetic skyrmions. In recent work, tailoring the shape of the bubbles is considered a key factor for their dynamics in spintronic devices. In addition to the reported circular, elliptical, and square bubbles, here we observe triangular bubble domains in bismuth-doped yttrium iron garnet(Bi-YIG) using Kerr microscopy. The bubble domains evolve from discrete circular to latticed triangular and hexagonal shapes. Further, the orientation of the triangular bubbles in the hexagonal lattices can be flipped by decreasing the magnetic field. The sixfold in-plane magnetic anisotropy of Bi-YIG(111) crystal, which is presumably the mechanism underlying the triangular shape of the bubbles, is measured as1179 erg/cm~3. The study of the morphologies of topologically trivial bubbles in YIG offers insight into nontrivial spin textures, which is appealing for future spintronic applications.
文摘Cerium-substituted yttrium iron garnet(Ce x Y 3-xFe 5O 12, Ce∶YIG) was prepared via coprecipitation. The structu re, morphology, valence state and constituent of Ce ions were investigated respe ctively. X-ray powder diffraction(XRD) analysis shows that Ce∶YIG was of singl e cubic YIG phase. The result of X-ray photoelectron spectroscopy(XPS) indicate s the Ce ions in Ce∶YIG were in the state of trivalence. Scanning electron micr oscope(SEM) demonstrates the conglobation of Ce∶YIG particles about 0.2μm scal e.The magnetic properties were studied by a vibrating sample magnetometer(VSM) a nd the result exhibits that substitution of Ce 3+ changes the magnetic para meters of YIG. The effects of doping content of Ce ions and synthesis temperatu re on valence control were discussed in detail.
文摘The principle and performance of a fiber-optic Faraday-effect magnetic-field sensor based on an yttrium iron garnet (YIG) and two flux concentrations are described. A single polarization-maintaining optical fiber links the sensor head to the source and detection system, in which the technique of phase shift cancellation is used to cancel the phase shift that accumulatein the optical fiber. Flux concentrators were exploited to enhance the YIG crystal magneto-optic sensitivity .The sensor system exhibited a noise-equivalent field of 8 pT/√Hz and a 3 dB bandwidth of ～10 MHz.
文摘Magneto-electric properties of the magnetic domains local areas of bismuth-substituted yttrium iron garnet films are investigated. The electromagneto-optical (EMO) scanning method was used in our experiments when probing by laser beam various sites of separate magnetic domains of the film. Registered in our experiments the nonlinear and linear components of EMO effect does not remain to constants at optical scanning of various points of the magnetic domain. I.e. the local EMOE picture from the separate sites of the domain must be more informative than an averaged one in the multidomain case.
基金Project supported by Joint Fund NSAF of National Natural Science Foundation of ChinaChina Academy ofEngineering Physics(U2130124)+1 种基金Shanghai Municipal Commission of Economy and Informatization,China(GYQJ-2020-1-19)theNational Natural Science Foundation of China(52172121)。
文摘Y_(3)Fe_(5)O_(12)(YIG)crystals are highly desirable for the fabrication of mid-infrared isolators with the rapid growth of optical communications,although it is rather challenging to grow large size and high-quality single crystals.Dy^(3+)doping is expected to improve the optical and magneto-optical prope rties.However,high quality Dy:YIG crystals and the adjustment of Dy^(3+)on the structure and optical behavior of YIG crystal remain unclear,impeding its practical applications.Herein,a series of Y_(3-x)Dy_(x)Fe_(5)O_(12)(x=0,0.5,1.0,1.5,3)solid solution crystals was grown by the flux-Bridgman method and single crystals up to 25 mm were obtained.With the introduction of Dy^(3+),lattice parameters are gradually enlarged from 1.2379 nm(YIG)to 1.2420 nm(DyIG).Typical Dy^(3+)absorption peaks are observed around 1070,1265 and 1670 nm.The refractive index decreases from 2.37(500 nm)to 2.10(2500 nm)for YIG crystal,and it reduces from 2.47(500 nm)to 2.16(2500 nm)for DyIG crystal.The optical bandgaps remain almost unchanged for Dy:YIG crystals.The optical dispersion of the refractive indices was finely fitted by the Wemple and DiDomenico(WDD)and the Sellmeier models,respectively.With the increase of Dy^(3+)content,the saturation magnetization(Ms)decreases significantly from 23.62 emu/g(YIG)to 5.33 emu/g(DyIG).Small coercive field is persisted for this system,endowing small external magnetic field.These results provide valuable references for the manipulation of rare earths on the properties of magnetooptical crystals,which is beneficial to the design of high-performance garnet crystals for the application of optical switching and non-reciprocal related devices.
基金Project supported by the Ministry of Finance Indonesia for the research grant through the competitive research program of RISPRO Kompetisi(PRJ-45/LPDP/2020)。
文摘Synthesis and characterization of lanthanum-doped yttrium iro n garnet(YIG)in the compositional se ries of Y_(3-x)La_(x)Fe_(5)O_(12)(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 an X-ray diffractometer,a scanning electron microscope,a vibrating sample magnetometer,and a Vector network analyzer.The results reveal that all compositions are crystallized into Y_(3)Fe_(5)O_(12)phase(space group la-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=0.0-0.5.The crystallite size of Y_(3-x)La_(x)Fe_(5)O_(12)series calculated by Scherrer method is found to decrease from 78 nm in x=0.0-63 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(M_(s))and remanence magnetization(M_(r))was studied.Due to the lanthanum substitution process,all La^(3+)-doped samples possess higher M_(s)and M_(r)values compared to the original composition.The results of Vector network analyzer show that the improvement of the M_(s)and M_(r)plays an important role in enhancing the microwave absorbing ability of the materials.The minimum RL changes 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 is mainly ascribed to the natural magnetic resonance loss and dipoIe-polarization loss due to the substitution process.The decreasing particle size also enhances the microwave absorbing ability of the La-doped samples via multiple-reflections mechanism.
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.
文摘A comprehensive study of the magnetic properties of Y3-2xCa2xFe5-xVxO12 (0 ≤ x ≤ 1) has been performed. The garnet ferrites samples were prepared by the ceramic technique, and X-ray diffraction analysis indicates the formation of single cubic phase. Vibrating sample magnetometry (VSM) and a superconducting quantum-interference device (SQUID) were used to measure the magnetic properties, especially the magnetization and thermo-magnetic behavior. The magnetization curves exhibit the typical characteristics of ferrimagnetic materials at both 4.2 K and at room temperature. The samples have a low coercivities (between 20 and 40 Oe) and saturation magnetizations as high as 36 emu/g at 4.2 K. The saturation magnetization decreases with V and Ca contents, reaching about 8 emu/g at 4.2 K (x = 1). For all samples, the saturation magnetization decreases with increasing temperature, whereas the Curie temperature increases for small values of x, from 557 K for x = 0 to a maximum of 590 K for x = 0.2. For larger values of x, it decreases and reaches 525 K for x = 1.0. The basic experimental trends reflect the occupancy of the tetrahedral 24d sites by vanadium in combination with the predominant intersublattice exchange constant Jad, although the nonzero magnetization at x = 1.0 indicates that about 10% of the substituted V atoms goes onto the octahedral 16a sites.
基金supported by the National Basic Research Program of China (Grant No. 2020YFA0309100)the National Natural Science Foundation of China (Grant Nos. 12074365 and U2032218)+3 种基金the Fundamental Research Funds for the Central Universities (Grant Nos. WK9990000108, WK9990000102, and WK2030000035)Hefei Science Center CAS Foundation (Grant No. 2021HSC-UE010)partially carried out at the USTC Center for Micro and Nanoscale Research and Fabricationthe magnetic characterizations were carried out in the Instruments Center for Physical Science, USTC。
文摘Y_(3)Fe_(5)O_(12)(YIG) and Bi Y_(3)Fe_(5)O_(12)(Bi:YIG) films were epitaxially grown on a series of(111)-oriented garnet substrates using pulsed laser deposition. Structural and ferromagnetic resonance characterizations demonstrated the high epitaxial quality, extremely low magnetic loss and coherent strain state in these films. Using these epitaxial films as model systems, we systematically investigated the evolution of magnetic anisotropy(MA) with epitaxial strain and chemical doping. For both the YIG and Bi:YIG films, the compressive strain tends to align the magnetic moment in the film plane while the tensile strain can compete with the demagnetization effect and stabilize perpendicular MA. We found that the strain-induced lattice elongation/compression along the out-of-plane [111] axis is the key parameter that determines the MA. More importantly, the strain-induced tunability of MA can be enhanced significantly by Bi doping;meanwhile, the ultralow damping feature persists. We clarified that the cooperation between strain and chemical doping could realize an effective control of MA in garnet-type ferrites, which is essential for spintronic applications.
文摘钇铁石榴石(yttrium iron garnet,YIG)的自旋输运特性一直是自旋电子学的研究重点之一.Bi作为YIG最常见的掺杂元素,其薄膜Bi_(x)Y_(3-x)Fe_(5)O_(12)的磁光特性已经被广泛研究.但Bi^(3+)取代Y^(3+)对YIG自旋输运的影响规律还没有被系统地研究过.本文利用溶液旋涂法制备了不同掺杂比的Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜,并研究Bi掺杂对YIG薄膜形貌结构和自旋输运性能的影响.结果表明Bi掺杂没有改变YIG的晶体结构,掺杂比上升令薄膜的吸收强度增大,带隙减小.XPS表明了Bi^(3+)和Bi^(2+)的存在.Bi掺杂在自旋输运上的调控体现在Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜的磁振子扩散长度相比纯YIG薄膜有所减小.同时研究发现Pt/Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜中依然可以检测到明显的自旋霍尔磁电阻,并在x=0.3时振幅最大.
基金financial support of this work from University of Kashan by Grant No. 363030/12
文摘In this work,we present a new and fast method to obtain the single phase YFeO(YIG,cubic) and YFeO(YIP, orthorhombic) nanocrystals based on hydrothermal technique. The influence of initial Y/Fe mole ratio and calcination temperature on the nature, purity, phase structure, and morphology of the product was investigated by X-ray diffraction(XRD), Fourier-transform infrared(FT-IR) spectroscopy,energy-dispersive(EDX) X-ray spectroscopy, and field emission scanning electron microscopy(FESEM).The results show that the transformation of the as-synthesized YIG from amorphous to orthorhombic and finally to cubic phase occurs with the increase of annealing temperature. On this basis, the pure cubic phase YIG can be obtained by calcination(at 1100℃) of the precursor which is prepared using the hydrothermal treatment of mole ratio of Y:Fe = 1:1.5 exposure to an ammonia atmosphere. Also, the initial Y/Fe mole ratio of 1:1 and calcination temperature of 1000 ℃ are the optimal conditions to form single-phase nanocrystalline YIP. Further, vibrating sample magnetometry(VSM) measurements illustrate the average magnetic saturation, coercivity and remanence of 2.73 and 15.00 emu/g, 42.74 and40.02 Oe, and 1.65 and 4.30 emu/g for YIP and YIG nanocrystals, revealing their soft ferromagnetic character.
