56 results on '"Zhaocong Huang"'
Search Results
2. Magnetic Field Modulated Ultrafast Spin Dynamics at Ni80Fe20/Neodymium Interface
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Lulu Cao, Zhaocong Huang, Yuting Gong, Qingjie Guo, Milad Jalali, Jun Du, Yongbing Xu, Qian Chen, XIANYANG LU, and Y Zhai
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Atomic and Molecular Physics, and Optics - Published
- 2023
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3. Preparation of sputtered Fe3O4 thin film
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Biao You, Ya Zhai, Andrew T. S. Wee, Xiaochao Zhou, Lulu Cao, Zhaoxia Kou, Wen Zhang, Qingjie Guo, Xiaojiang Yu, Jun Du, Jian Liang, Qi Li, Zhaocong Huang, Ping Kwan Johnny Wong, and Huihui Zhao
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Materials science ,Spintronics ,Analytical chemistry ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,symbols.namesake ,X-ray photoelectron spectroscopy ,Ferrimagnetism ,Sputtering ,symbols ,Texture (crystalline) ,Electrical and Electronic Engineering ,Thin film ,Raman spectroscopy ,Diffractometer - Abstract
Fe3O4, as a half-metallic ferrimagnetic material, is believed to be one of the most promising materials in spin transport for spintronics. However, fabricating stoichiometric Fe3O4 film is still challenging because the oxidation is hard to control for various preparing methods. In this paper, series of Fe3O4 thin films on Si (100) substrates are grown by sputtering from a Fe3O4 target without oxygen atmosphere at different growth temperature and then extra heat treatment in high vacuum. By combining X-ray diffractometer (XRD), Raman spectrum, X-ray photoelectron spectroscopy and X-ray magnetic circular dichroism, VSM analysis, we see that the structure and magnetic moment of Fe3O4 film are not only related with growth temperature during sputtering, but also refer to the temperature of post-heat treatments. When the growth temperature is lower than 300 °C, the film does not show any XRD diffraction peaks. When the growth temperature increases from 300 to 500 °C, the film shows the (111) texture of Fe3O4 film clearly. However, the other XRD diffraction peaks are observed after post-heat treatment. The saturation magnetization increases with growth temperature and the largest saturation magnetization is 473 emu/cm3 for growth temperature of 450 °C and extra heat treatment, which is close to bulk Fe3O4. Our results suggest that a selectable method can be used to fabricate high magnetic moment of Fe3O4 thin film.
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- 2021
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4. Spin Dynamic Damping of Py Induced by Gd Capping
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Fengxian Wang, Zhaocong Huang, Ya Zhai, Jian Liang, Chaoxia Kou, Qian Chen, Jun Du, Mingming Tian, and Wei Shen
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010302 applied physics ,Permalloy ,Materials science ,Magnetic moment ,Magnetoresistance ,Condensed matter physics ,Bilayer ,Gadolinium ,chemistry.chemical_element ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,chemistry ,0103 physical sciences ,Proximity effect (superconductivity) ,Magnetic memory ,Electrical and Electronic Engineering ,Spin (physics) - Abstract
Magnetic dynamic damping is significantly important in determining the relaxation time of magnetic moments and the speed of magnetic memory devices. Here, magnetic dynamic behaviors of permalloy (Py) films capped with gadolinium (Gd) are studied, and the effects of the interface are investigated by the Cu insert layer. For Py/Gd bilayer films, both the saturation magnetization ( ${M}_{s}$ ) and the surface anisotropy constant ( ${K}_{{\bot }}$ ) are decreased with increasing Gd thickness, while the Gilbert damping ( $\alpha$ ) is enhanced. With the insert of Cu at Py/Gd interface, the above tendencies of ${M}_{s}$ , ${K}_{\bot }$ , and $\alpha $ are suppressed. We attribute these phenomena to the antiferromagnetic coupling between Gd and Py near the interface, which are caused by the magnetic proximity effect (MPE) instead of the spin relaxation in the rare earth Gd themselves.
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- 2021
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5. Current-Direction-Dependent Depinning of Vortex Domain Walls in Permalloy Zigzag Nanowires
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Zhaocong Huang, Jiai Ning, Ya Zhai, Liang He, Shaolong Tang, Yongbing Xu, Leyi Chen, and Xiaochao Zhou
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010302 applied physics ,Permalloy ,Materials science ,Condensed matter physics ,Magnetic domain ,Nanowire ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Vortex ,Magnetization ,Amplitude ,Zigzag ,0103 physical sciences ,Electrical and Electronic Engineering ,Current density - Abstract
We investigate the current induced depinning of magnetic domain walls (DWs) trapped at the kinks in a patterned Py nanowire with two-kink zigzag shape on Si/SiO2 substrate. By injecting pulse current with varying amplitude, two threshold current densities with a slight difference of around $6 \times 10^{10}$ A m−2 have been determined according to the different depinning process. The smaller threshold current density corresponds to the depinning of a single DW which is always the first DW facing to the electron flow. This fact indicates that the different pinning potential caused by the structural asymmetry is not the key to determine which DW is to depin. Micromagnetic simulations provide evidence that the specific current-driven behavior of the vortex DW might account for the single depinning process. The larger threshold corresponds to the simultaneous depinning of two DWs which has been commonly observed in a variety of shaped nanowires. This asynchronous depinning phenomenon provides the possibility of the selective DW depinning in the future logic devices.
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- 2021
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6. Two dimensional CrGa2Se4: a spin-gapless ferromagnetic semiconductor with inclined uniaxial anisotropy
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Jinlan Wang, Haowei Wang, Zhaocong Huang, Liang Ma, Ruqian Wang, Qian Chen, and Shijun Yuan
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Condensed Matter::Materials Science ,Phase transition ,Magnetic anisotropy ,Materials science ,Condensed matter physics ,Spintronics ,Ferromagnetism ,Magnetism ,Curie temperature ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Magnetic semiconductor ,Anisotropy - Abstract
Magnetic semiconductors with high critical temperature have long been the focus in materials science and are also known as one of the fundamental questions in two-dimensional (2D) materials. Based on density functional theory calculations, we predict a 2D spin-gapless ferromagnetic semiconductor of CrGa2Se4 monolayer, in which the type of spin-polarized current can be tuned by tailoring the Fermi energy. Moreover, the magnetic anisotropy energy calculations indicate that the CrGa2Se4 monolayer possesses spin anisotropy both in the basal plane and the vertical plane. This originates from the distortion-induced rearrangement of the 3d electrons in the CrSe6 octahedron and results in an inclined easy axis out of the film. The Curie temperature (Tc) of ferromagnetic phase transition for 2D CrGa2Se4 is more than 200 K. This 2D material shows promising transport properties for spintronics applications and is also important for fundamental research in 2D magnetism.
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- 2021
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7. Proximity effect of a two-dimensional van der Waals magnet Fe3GeTe2 on nickel films
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Zhongming Zeng, Jian Liang, Qian Chen, Bin Fang, Baoshun Zhang, Zhaocong Huang, Yonghui Zhu, Ya Zhai, Wenxing Lv, Jialin Cai, Weiming Lv, and Jiachen Wang
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Materials science ,Condensed matter physics ,Spintronics ,Magnetism ,chemistry.chemical_element ,Ferromagnetic resonance ,Condensed Matter::Materials Science ,Nickel ,symbols.namesake ,chemistry ,Magnet ,Magnetic damping ,symbols ,General Materials Science ,van der Waals force ,Proximity effect (atomic physics) - Abstract
Recent advances in two-dimensional van der Waals (2D vdW) magnets provide new platforms to study their magnetism in reduced dimensions. However, most of the studies performed to date have been limited to low temperatures. Here, we report the proximity effect of a 2D vdW magnet Fe3GeTe2 (FGT) on nickel (Ni) films at room temperature. Ferromagnetic resonance measurements show that FGT can increase the perpendicular magnetic anisotropy (PMA) and magnetic damping of the adjacent Ni film. Such an interfacial effect is observed at room temperature, and becomes more pronounced as the temperature decreases. A similar effect is also achieved in another 2D heterostructure of Cr2Ge2Te6/Ni, implying its universality in a variety of 2D magnetic materials. Our work provides a new approach for utilizing 2D magnets in spintronics at room temperature.
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- 2021
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8. Magnetism and spin transport at permalloy/Cu1−xTbx interfaces
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Sheng Jiang, Zhaocong Huang, Qi An, Wen Zhang, Yuli Yin, Dong Zhang, Jun Du, Biao You, Jian-Guo Zheng, Wenqing Liu, and Ya Zhai
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- 2022
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9. Programmable Gilbert Damping in Py /Cu/Fe - Co - Tb Structures with Dynamic Interlayer Coupling
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Qian Chen, Qingjie Guo, Wen Zhang, Ping Kwan Johnny Wong, Zhaocong Huang, Zhaoxia Kou, Jun Du, Zhongming Zeng, and Ya Zhai
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General Physics and Astronomy - Published
- 2022
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10. Magnetization dependent spin orbit torques generated by ferrimagnetic FeCoTb alloys
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Qian Chen, Qingjie Guo, Zhaocong Huang, Bin Fang, Shangkun Li, Weiming Lv, Rongxin Li, Yi Luo, Jun Du, Baoshun Zhang, Ya Zhai, Yaming Fan, and Zhongming Zeng
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Mechanics of Materials ,Mechanical Engineering ,Materials Chemistry ,Metals and Alloys - Published
- 2023
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11. Effective spin dynamic control of CoFeB/Nd heterostructure by matched resistivity
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Jian Liang, Qian Chen, Qingjie Guo, Wei Jiang, Zhaocong Huang, Biao You, Jun Du, and Ya Zhai
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Physics and Astronomy (miscellaneous) - Abstract
The spin dynamics modulation has attracted extensive attention in the past decades. Rare-earth (RE) metals are essential participants in this context due to the large spin–orbit coupling. Here, with neodymium (Nd) capping, we achieve the enhancement on spin dynamic damping of Co40Fe40B20 (CFB) films by three times larger than that of CFB single layer. Based on the spin pumping theory, the interfacial spin mixing conductance [Formula: see text] is calculated as 7.3 × 1015 cm−2, which is one order larger than that of CFB/Pt. It leads to the large spin current transparency at CFB/Nd interface. By comparing of the resistivity of each layer, we found that the matched resistivity at two sides of the CFB/Nd interface plays an important role in the enhancement of [Formula: see text]. As a consequence, a high spin transparency of the CFB/Nd interface is obtained as 82%. In addition, damping enhancement of CFB is not changed promptly by inserting 1–2 nm Cu layer, but it is suppressed when the Cu layer is thicker than 3 nm, which is related to the thickness dependence of the Cu resistivity. Our study broadens the horizon for the application of rare-earth (RE) in spintronics.
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- 2022
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12. Large spin hall conductivity in low-symmetry semiconductor ZrSe3
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Yonghui Zhu, Qian Chen, Haijing Wu, Jian Liang, Mingming Tian, Wei Jiang, Jiachen Wang, Rongxin Li, Shangkun Li, Zhaocong Huang, Zhaoxia Kou, Weiming Lv, Baoshun Zhang, Zhongming Zeng, and Ya Zhai
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Mechanics of Materials ,Mechanical Engineering ,Materials Chemistry ,Metals and Alloys - Published
- 2022
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13. Proximity effect of a two-dimensional van der Waals magnet Fe
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Qian, Chen, Jian, Liang, Bin, Fang, Yonghui, Zhu, Jiachen, Wang, Weiming, Lv, Wenxing, Lv, Jialin, Cai, Zhaocong, Huang, Ya, Zhai, Baoshun, Zhang, and Zhongming, Zeng
- Abstract
Recent advances in two-dimensional van der Waals (2D vdW) magnets provide new platforms to study their magnetism in reduced dimensions. However, most of the studies performed to date have been limited to low temperatures. Here, we report the proximity effect of a 2D vdW magnet Fe
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- 2021
14. Effect of Dilute Rare-Earth Doping on Magnetodynamic Properties of Permalloy Films
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Ya Zhai, Zhaocong Huang, Honglei Yuan, Jun Du, Yuli Yin, Xiaochao Zhou, and Qian Chen
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010302 applied physics ,Permalloy ,Materials science ,Spintronics ,Condensed matter physics ,Dopant ,Doping ,01 natural sciences ,Ferromagnetic resonance ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Condensed Matter::Superconductivity ,0103 physical sciences ,Magnetic damping ,Perpendicular ,Coupling (piping) ,Condensed Matter::Strongly Correlated Electrons - Abstract
Tunable magnetodynamic properties of magnetic materials will allow significant design freedom in spintronic devices. One of the most efficient methods to tailor magnetic properties is by element doping. Here, we study the effect of rare-earth (RE) doping on Permalloy (Py) films to modify the magnetic damping and exchange stiffness by both the ferromagnetic resonance uniform precession mode and the first perpendicular standing spin-wave mode. Results show that both static and dynamic magnetic properties of Py films are adjusted by doping with Gd, Tb, and Nd. The saturation magnetization is decreased by 59.4% with Tb, Gd, and Nd at concentrations of 10 at.%. The magnetic damping coefficient (α) is enhanced mostly by Tb dopant, followed by Nd and Gd, indicating that spin-orbit coupling may be one of the main mechanisms in determining α of RE-doped films. A 44.2% reduction of the exchange stiffness was achieved by doping with 3.3 at.% Nd. The results demonstrate that RE doping may be a viable technique for the control of magnetodynamic properties for spintronics applications.
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- 2019
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15. Two dimensional CrGa
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Qian, Chen, Ruqian, Wang, Zhaocong, Huang, Shijun, Yuan, Haowei, Wang, Liang, Ma, and Jinlan, Wang
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Magnetic semiconductors with high critical temperature have long been the focus in materials science and are also known as one of the fundamental questions in two-dimensional (2D) materials. Based on density functional theory calculations, we predict a 2D spin-gapless ferromagnetic semiconductor of CrGa
- Published
- 2021
16. Effective tuning of spin mixing conductance at the Py/Cu–Nd interface
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Qian Chen, Lulu Cao, Jinji Li, Qiang Fu, Yonghui Zhu, Qingjie Guo, Ruobai Liu, Tian Li, Wen Zhang, Jun Du, Jianguo Zheng, Zhaocong Huang, Ping Kwan Johnny Wong, Bin Fang, Zhongming Zeng, and Ya Zhai
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Physics and Astronomy (miscellaneous) - Abstract
Spin mixing conductance (SMC) at the ferromagnetic/non-magnetic material (FM/NM) interface governs the transport efficiency of the spin current. A high level of SMC is crucial for efficient spin injection and spin manipulation. Here, we report a reliable way to enhance the SMC at the FM/NM interface by rare-earth doping in the NM layer. As evidenced by the decreased saturation magnetization in permalloy (Py)/Cu–Nd structures, an induced magnetism in Nd is proposed, which is likely to be antiferromagnetically coupled to Py at the interface. By changing the doping content of Nd, the Py/Cu–Nd interface can be well designed, which gives rise to an effective tuning of the SMC from 0.37 × 1015 to 16.26 × 1015 cm−2. Such a tuning effect of SMC is suppressed by inserting a Cu spacer, demonstrating the key role of the antiferromagnetically coupled interface to the improved SMC. Our results highlight the significance of rare-earth materials in spin transport, expanding the design capability of energy-efficient spintronic devices.
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- 2022
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17. Direct observation of spin polarization in epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering
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Zhe Zhang, Xianyang Lu, Yu Yan, Jiahua Lu, Zhuoyi Li, Qi Liu, Fangyuan Zhu, Jiefeng Cao, Yong Wang, Zhaocong Huang, Ya Zhai, Yao Li, Xuezhong Ruan, Liang He, Jing Wu, Jun Du, Rong Zhang, and Yongbing Xu
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Physics and Astronomy (miscellaneous) - Abstract
We obtained epitaxial single-crystal Fe3O4(001)/MgO(001) thin films by magnetron sputtering. The high quality of the grown Fe3O4 films was confirmed by reflection high-energy electron diffraction and x-ray photoelectron spectroscopy. Atomic magnetic properties of Fe3O4(001)/MgO(001) were investigated using vibrating sample magnetometry and x-ray magnetic circular dichroism. The values of saturation magnetization and magnetic moment are 407 [Formula: see text] 5 emu/cm3 (3.26 [Formula: see text] 0.04 [Formula: see text]) and 3.31 [Formula: see text] 0.15 [Formula: see text], respectively, in the Fe3O4 film as thin as 5 nm, which are close to the bulk values. The spin polarization was directly measured using spin-resolved photoemission spectroscopy. The measured spin polarization has a maximum value of −42% [Formula: see text] 3%, which is comparable to the theoretical value for the ([Formula: see text] × [Formula: see text])R45° reconstructed Fe3O4(001) surface. Furthermore, the film thickness-dependent measurements indicate that the anti-phase boundaries significantly decrease the spin polarization rather than the lattice mismatch. Our results demonstrate that epitaxial Fe3O4(001)/MgO thin films grown by magnetron sputtering have desired magnetic properties, facilitating the potential application of Fe3O4-based spintronic devices.
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- 2022
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18. Spin transport in epitaxial Fe3O4/GaAs lateral structured devices
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Zhaocong Huang, Wenqing Liu, Jian Liang, Qingjie Guo, Ya Zhai, and Yongbing Xu
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General Physics and Astronomy - Abstract
Research in the spintronics community has been intensively stimulated by the proposal of the spin field-effect transistor (SFET), which has the potential for combining the data storage and process in a single device. Here we report the spin dependent transport on a Fe3O4/GaAs based lateral structured device. Parallel and antiparallel states of two Fe3O4 electrodes are achieved. A clear MR loop shows the perfect butterfly shape at room temperature, of which the intensity decreases with the reducing current, showing the strong bias dependence. Understanding the spin-dependent transport properties in this architecture has strong implication in further development of the spintronic devices for room-temperature SFETs.
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- 2022
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19. Large anisotropy of magnetic damping in amorphous CoFeB films on GaAs(001)
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Ya Zhai, Hongqing Tu, Jun Du, Rongkun Zheng, Wei Zhang, Yuan Yuan, Ruobai Liu, Zhaocong Huang, Zongzhi Zhang, Biao You, Jiangtao Qu, Ji Wang, and Zhendong Zhu
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Damping ratio ,Materials science ,Kerr effect ,Condensed matter physics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Ferromagnetic resonance ,Amorphous solid ,Condensed Matter::Materials Science ,Magnetic anisotropy ,0103 physical sciences ,Magnetic damping ,General Materials Science ,010306 general physics ,0210 nano-technology ,High-resolution transmission electron microscopy ,Anisotropy - Abstract
Amorphous CoFeB films grown on GaAs(001) substrates demonstrating significant in-plane uniaxial magnetic anisotropy were investigated by vector network analyzer ferromagnetic resonance. Distinct in-plane anisotropy of magnetic damping, with a largest maximum-minimum damping ratio of about 109%, was observed via analyzing the frequency dependence of linewidth in a linear manner. As the CoFeB film thickness increases from 3.5 nm to 30 nm, the amorphous structure for all the CoFeB films is maintained while the magnetic damping anisotropy decreases significantly. In order to reveal the inherent mechanism responsible for the anisotropic magnetic damping, studies on time-resolved magneto-optical Kerr effect and high resolution transmission electron microscopy were performed. Those results indicate that the in-plane angular dependent anisotropic damping mainly originates from two-magnon scattering, while the Gilbert damping keeps almost unchanged.
- Published
- 2020
20. Thermal excitation studies on the silica coating magnetite composite microspheres with Mössbauer spectra and first principle calculations
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Zhaocong Huang, Biao You, Jun Du, Wenbiao Chao, Lulu Cao, Zhaoxia Kou, Ya Zhai, and Shijun Yuan
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Magnetization ,Materials science ,Magnetic moment ,Phase (matter) ,Analytical chemistry ,Magnetic nanoparticles ,Particle size ,Absorption (chemistry) ,Condensed Matter Physics ,Hyperfine structure ,Grain size ,Electronic, Optical and Magnetic Materials - Abstract
Fe3O4 nanomaterials have attracted lastest interests due to their excellent properties and potential applications. In this paper, the thermal excitation is investigated by Mossbauer spectra and first principle calculations. Fe3O4 nanoparticles with uniform size, regular shape and good dispersibility are prepared by the solvothermal methods, and Fe3O4@SiO2 composite magnetic particles with layers of mesostructured SiO2 structure are assembled by improved Stober method. The particle size is 500 nm and the shell thickness of SiO2 layer is 80 nm. Fe3O4@SiO2 composite magnetic particles are then annealed at different temperature of 200 °C, 400 °C and 600 °C. The experimental measurements exhibit that the grain size grows up, and the magnetization is enhanced significantly, with increasing heat treatment temperature. However, Mossbauer spectra show that the relative absorption intensity in B-site fast decreases as increasing heat treatment temperature, from 64% at room temperature to 27% at 600 °C, indicating that large amount of Fe vacancies may form in B-site, and correspondingly, the net magnetic moment due to the difference of amount of Fe in B and A sites would be reduced, which strongly disagrees with the results of magnetization measured by vibrating sample magnetometer. In order to find the mechanism behind magnetization, the first-principle calculations are performed and reveal that the oxygen ions in the SiO2 shell may go into Fe3O4 core, which causes number of Fe2+ ions to decreases and transfer to Fe3+ ions, leading to the increase of magnetic moment. So we classify the difference between the amount of Fe3+ and Fe2+ ions in B-site as γ-Fe2O3. Based on this, Mossbauer spectra analysis presents quantitatively the concentration of various phase and their hyperfine interactions. This work provides a method to analyze the magnetic moment of Fe3O4.
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- 2022
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21. Anisotropic magnetoresistance in room temperature ferromagnetic single crystal CrTe flake
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Ya Zhai, Mingming Tian, Yongbing Xu, Ruobai Liu, Yutian Yang, Qian Chen, Zhenhua Ni, Shasha Sun, Jian Liang, Lulu Cao, Wei Shen, Zhaocong Huang, Jun Du, Haijing Wu, and Weiwei Lin
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Materials science ,Magnetoresistance ,Condensed matter physics ,Spintronics ,Mechanical Engineering ,Metals and Alloys ,Chemical vapor deposition ,Condensed Matter::Materials Science ,Magnetization ,Ferromagnetism ,Electrical resistance and conductance ,Mechanics of Materials ,Magnet ,Materials Chemistry ,Single crystal - Abstract
Chromium tellurides have triggered tremendous investigations in physics and materials science, where their unique properties offer excellent opportunities for spintronic applications. Here, we report anisotropic magnetoresistance (AMR) of ferromagnetic CrTe single crystal flake grown by chemical vapor deposition. An individual hexagonal flake exhibits an easy magnetization axis along its normal direction, and cooling from room temperature to low temperature, its electrical resistance measured with the magnetization parallel to current geometry is larger than that for the perpendicular to the current geometry, indicating the presence of an AMR behavior. The AMR ratio has been found to increase with decreasing temperature and is 5.2% at 5 K, comparable with general magnetic transition metal and alloy. This suggests CrTe single crystal flake to be a promising magnetic material for spintronics applications.
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- 2022
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22. Influence of Cr layer thickness on the static and dynamic performances of Tb/Cr/Ni80Fe20 structure
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Jinjin Yue, Zhaocong Huang, Qian Chen, Li Sun, Sheng Jiang, Zhongyu Yao, Hongru Zhai, Xiaochao Zhou, Ya Zhai, Yongjia Xu, and Qiannan Li
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Materials science ,Condensed matter physics ,Magnetometer ,Mechanical Engineering ,Gyromagnetic ratio ,Metals and Alloys ,Resonance ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Magnetic hysteresis ,01 natural sciences ,Ferromagnetic resonance ,law.invention ,Magnetization ,Mechanics of Materials ,law ,0103 physical sciences ,Proximity effect (audio) ,Materials Chemistry ,010306 general physics ,0210 nano-technology ,Anisotropy - Abstract
Using the vibrating sample magnetometer and ex situ vector network analyzer ferromagnetic resonance, the static and dynamic magnetic properties of Tb (4 nm)/Cr ( t Cr )/Ni 80 Fe 20 (12 nm) trilayers with different thickness of Cr layer (from 0.2 to 4.0 nm) were investigated comparing with those of Ni 80 Fe 20 film. From the results of in-plane static magnetic hysteresis loops, we analyzed the soft magnetic properties and in-plane anisotropy, along with obtaining the saturation magnetization ( M s ) which shows no obvious reducing and a modulation akin to RKKY coupling. By fitting the relationship of resonance field and linewidth versus resonance frequency, the effective magnetization 4π M eff , gyromagnetic ratio γ , and effective damping coefficient ( α eff ) were extracted. It is worthwhile to mention that the inserting of ultrathin Cr layer (0.2 nm) enhanced the above parameters obviously, which then backed down towards their values in Ni 80 Fe 20 film with increasing the thickness of Cr layer as a result of the weakening magnetic proximity effect and the decreasing spin-pumping effect in trilayers. Finally, they became flattening with the Cr layer thicker than 1 nm where oscillations are also observed in the value of γ and α eff. Interestingly, the oscillations in α eff and γ are consistent with each other, which implies the damping mechanism mainly related to the spin-orbit coupling originating from the indirect interaction between Tb and Ni 80 Fe 20 . In addition, the inhomogeneous broadening (Δ H 0 ) were determined to be very small which further ascertain the accurate of the α eff .
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- 2017
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23. Effect of Zn substitution in (111)-textured ZnxFe3−xO4 thin films on magnetization dynamics
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Er Liu, Honglei Yuan, Yuli Yin, Hongru Zhai, Ya Zhai, Jun Du, Jian-Guo Zheng, and Zhaocong Huang
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010302 applied physics ,Magnetization dynamics ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Doping ,Metals and Alloys ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ferromagnetic resonance ,Pulsed laser deposition ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Mechanics of Materials ,0103 physical sciences ,Materials Chemistry ,Texture (crystalline) ,Thin film ,0210 nano-technology ,High-resolution transmission electron microscopy - Abstract
The strong (111)-textured ZnxFe3−xO4 thin films were grown on SiO2-terminated silicon substrates using pulsed laser deposition. X-ray diffraction and high resolution transmission electron microscopy clearly show the column growth structure along the film thickness direction in [111] crystalline orientation for every grain column. With the introduction of texture induced magnetic anisotropy in the free energy density model, we quantitatively determined the doping effect on the various anisotropies in (111)-textured ZnxFe3−xO4 films. The mechanisms of ferromagnetic resonance linewidth of ZnxFe3−xO4 thin films are investigated by the theoretical fitting, in which considering the contributions from intrinsic spin-orbit coupling, extrinsic compositions from two-magnon scattering and inhomogeneous broadening. It is found that the Gilbert damping coefficient α increases with increasing Zn substitution x from 0 to 0.3, indicating that the spin-orbit coupling of the ZnxFe3−xO4 thin films increases with the introduction of Zn impurities.
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- 2017
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24. Ferromagnet/Two-Dimensional Semiconducting Transition-Metal Dichalcogenide Interface with Perpendicular Magnetic Anisotropy
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Feng Xu, Er Liu, Stephen J. Pennycook, Gerrit van der Laan, Shengwei Zeng, Jiaren Yuan, Ya Zhai, Hongyu Wang, Rebekah Chua, Ashutosh Rath, Daniel H. C. Chua, Ariando, Ping Kwan Johnny Wong, Simon A. Morton, Yuan Ping Feng, Lei Zhang, Wen Zhang, Andrew Ts Wee, Xiaochao Zhou, and Zhaocong Huang
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Materials science ,perpendicular magnetic anisotropy ,General Physics and Astronomy ,02 engineering and technology ,010402 general chemistry ,Epitaxy ,01 natural sciences ,Transition metal ,anisotropic orbital moment ,General Materials Science ,two-dimensional materials ,Nanoscience & Nanotechnology ,Spin-½ ,spintronics ,Spintronics ,Magnetic moment ,Condensed matter physics ,Magnetic circular dichroism ,General Engineering ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Ferromagnetism ,X-ray magnetic circular dichroism ,transition-metal dichalcogenides ,interface ,0210 nano-technology - Abstract
Ferromagnet/two-dimensional transition-metal dichalcogenide (FM/2D TMD) interfaces provide attractive opportunities to push magnetic information storage to the atomically thin limit. Existing work has focused on FMs contacted with mechanically exfoliated or chemically vapor-deposition-grown TMDs, where clean interfaces cannot be guaranteed. Here, we report a reliable way to achieve contamination-free interfaces between ferromagnetic CoFeB and molecular-beam epitaxial MoSe2. We show a spin reorientation arising from the interface, leading to a perpendicular magnetic anisotropy (PMA), and reveal the CoFeB/2D MoSe2 interface allowing for the PMA development in a broader CoFeB thickness-range than common systems such as CoFeB/MgO. Using X-ray magnetic circular dichroism analysis, we attribute generation of this PMA to interfacial d-d hybridization and deduce a general rule to enhance its magnitude. We also demonstrate favorable magnetic softness and considerable magnetic moment preserved at the interface and theoretically predict the interfacial band matching for spin filtering. Our work highlights the CoFeB/2D MoSe2 interface as a promising platform for examination of TMD-based spintronic applications and might stimulate further development with other combinations of FM/2D TMD interfaces.
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- 2019
25. Investigation on interfacial effect of CoFeB/GaAs heterostructure
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Jian Liang, Fengxian Wang, Xiaochao Zhou, Ya Zhai, Biao You, Qian Chen, Zhaocong Huang, Guangyu Wang, Wei Jiang, Qingyu Xu, Zhaoxia Kou, and Jun Du
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Materials science ,Condensed matter physics ,Field (physics) ,business.industry ,Mechanical Engineering ,Schottky barrier ,Metals and Alloys ,Heterojunction ,02 engineering and technology ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Amorphous solid ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Semiconductor ,Ferromagnetism ,Mechanics of Materials ,Materials Chemistry ,0210 nano-technology ,business ,Quantum tunnelling - Abstract
Interfacial effect of amorphous cobalt-iron-boron (Co60Fe20B20) films deposited on GaAs(001) by DC magnetron-sputtering has been precisely studied. In-plane uniaxial magnetic anisotropy (UMA) as a significant magnetic property has been found in Co60Fe20B20/GaAs heterostructure and the UMA field (Hu) of (∼75 Oe) is achieved. Magnetic Schottky barrier contact has been achieved by current-voltage (I–V) characteristic through the interface with a barrier height of 0.72 eV, which is an appropriate for tunneling injection of spin current from ferromagnet to semiconductors in spin-injection devices.
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- 2021
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26. Enhancing the Spin–Orbit Coupling in Fe3O4 Epitaxial Thin Films by Interface Engineering
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Baoping Wang, Qionghua Zhou, Wen Zhang, Zhaocong Huang, Qian Chen, Shuai Dong, Jinjin Yue, Ya Zhai, Wenqing Liu, Y. X. Lu, Yunxia Sui, Jinlan Wang, and Yongbing Xu
- Subjects
Materials science ,Condensed matter physics ,Condensed Matter::Other ,Magnetic circular dichroism ,Ionic bonding ,02 engineering and technology ,Substrate (electronics) ,Spin–orbit interaction ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,Ferromagnetic resonance ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Condensed Matter::Superconductivity ,0103 physical sciences ,General Materials Science ,Thin film ,010306 general physics ,0210 nano-technology - Abstract
By analyzing the in-plane angular dependence of ferromagnetic resonance linewidth, we show that the Gilbert damping constant in ultrathin Fe3O4 epitaxial films on GaAs substrate can be enhanced by thickness reduction and oxygen vacancies in the interface. At the same time, the uniaxial magnetic anisotropy due to the interface effect becomes significant. Using the element-specific technique of X-ray magnetic circular dichroism, we find that the orbital-to-spin moment ratio increases with decreasing film thickness, in full agreement with the increase in the Gilbert damping obtained for these ultrathin single-crystal films. Combined with the first-principle calculations, the results suggest that the bonding with Fe and Ga or As ions and the ionic distortion near the interface, as well as the FeO defects and oxygen vacancies, may increase the spin–orbit coupling in ultrathin Fe3O4 epitaxial films and in turn provide an enhanced damping.
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- 2016
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27. Erratum: 'Interlayer transmission of magnons in dynamic spin valve structures' [Appl. Phys. Lett. 116, 132403 (2020)]
- Author
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Zhaocong Huang, Zhaoxia Kou, Yongbing Xu, Ya Zhai, Xuezhong Ruan, Honglei Yuan, Qian Chen, and Xiaochao Zhou
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Transmission (telecommunications) ,Condensed matter physics ,Magnon ,Spin valve - Published
- 2020
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28. Interlayer transmission of magnons in dynamic spin valve structures
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Qian Chen, Xuezhong Ruan, Zhaocong Huang, Zhaoxia Kou, Yongbing Xu, Xiaochao Zhou, Honglei Yuan, and Ya Zhai
- Subjects
010302 applied physics ,Magnonics ,Work (thermodynamics) ,Materials science ,Kerr effect ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Spintronics ,Condensed Matter::Other ,Magnon ,Spin valve ,02 engineering and technology ,Dissipation ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Condensed Matter::Materials Science ,Transmission (telecommunications) ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,0210 nano-technology - Abstract
Magnonic devices are promising alternatives to conventional charge-current-driven spintronic devices. As the basic unit of spintronic devices, the spin valve is of limited use in magnonics because its dynamics is rarely studied. Here, we investigate the interlayer transmission of magnons in dynamic spin valve structures using the time-resolved magneto-optical Kerr effect. Interaction between magnons and the interfacial dissipation are studied by comparing three samples with different spin valve structures. Magnons with different intrinsic frequencies have strong interactions. In contrast, magnons with similar intrinsic frequencies have relatively weak interactions. Interfacial dissipations of magnons are increased by rare earth insertion, which can reduce the interactions between magnons indirectly. This work extends the application of spin valve structures to magnonic devices beyond their conventional use.
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- 2020
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29. Effect of substrate temperature on antiphase boundaries and spin polarization of thin Fe3O4 film on Si (100)
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Er Liu, Hongyan Peng, Li Sun, Hongru Zhai, Zhongyu Yao, Xiaoyan Li, Zhaocong Huang, Dongmei Ban, and Ya Zhai
- Subjects
010302 applied physics ,Materials science ,Magnetoresistance ,Spin polarization ,Metals and Alloys ,Analytical chemistry ,02 engineering and technology ,Surfaces and Interfaces ,Substrate (electronics) ,Activation energy ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,law.invention ,law ,0103 physical sciences ,Materials Chemistry ,Crystallite ,Crystallization ,0210 nano-technology ,Superparamagnetism - Abstract
Polycrystalline Fe3O4 films with the thickness of 27 nm were grown at different temperature (Ts) on Si (100) substrate by Laser-Molecular Beam Epitaxy to study the influence of density of antiphase boundaries (APBs) and the spin polarization of Fe3O4. Films prepared with Ts in the range of 500 °C - 650 °C were proved to be of good crystallization, preferred orientation, and desirable values of saturation magnetization (a little smaller one for film prepared at Ts = 500 °C). The lowest density of APBs was verified by the measured bulk like electron-phonon (s-p) coupling constant for film prepared at Ts = 550 °C, along with the highest value of spin polarization and the best crystalline quality as the most obvious inflection in the curves of lnρ vs. 1000/T around Verwey transition. This optimum value of Ts can be interpreted by the APBs thermally activated migration process with an activation energy. Films prepared with Ts = 500 °C, 600 °C, and 650 °C still have a reasonable value of the s-p coupling constant compared to recently reported results, while larger magnetoresistance accompanied by the superparamagnetic behavior was observed for films prepared at lower Ts (Ts = 400 °C and 450 °C).
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- 2020
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30. Investigation of Saturation Magnetization and Damping in Tb/Cr/Fe Trilayers
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Wen Zhang, Zhaocong Huang, Hongru Zhai, Yunxia Sui, Li Sun, Ping Kwan Johnny Wong, Dong Zhang, Ya Zhai, Jun Du, and Zhaoxia Kou
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Diffraction ,Magnetic anisotropy ,Materials science ,Condensed matter physics ,Magnetic moment ,Ferromagnetism ,Magnetometer ,law ,Electrical and Electronic Engineering ,Damping constant ,Ferromagnetic resonance ,Electronic, Optical and Magnetic Materials ,law.invention - Abstract
The Tb(4 nm)/Cr( ${t}$ nm)/Fe(5 nm) trilayers with different thicknesses of Cr layer have been investigated by X-ray diffraction, vibrating sample magnetometer, and ferromagnetic resonance. When Cr is thinner than 1.8 nm, the ferromagnetic coupling of Tb and Fe leads to higher saturation magnetization ( $M_{s}$ ) than that of Fe(5 nm) film. On the other hand, the Gilbert damping constant $\alpha $ in all the trilayers have been found to exceed the magnitude of the Fe. In particular, when Cr layer is 1 nm thick, $\alpha $ increases by 38% and $M_{s}$ is increased by 6%; when Cr layer is 4 nm thick, $\alpha $ is increased by 46%, while $M_{s}$ is only decreased by 5%. Accordingly, we have demonstrated a way for enhancing damping and magnetic moment simultaneously in the Tb(4 nm)/Cr( ${t}$ nm)/Fe(5 nm) trilayers.
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- 2015
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31. An investigation on synthesis of Fe3O4@nSiO2@mSiO2 hybrid particles and peroxidation
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Xiaochao Zhou, Zhaoxia Kou, Wenbiao Chao, Jun Du, Zhaocong Huang, Biao You, Lulu Cao, Yanji Zhu, Ya Zhai, and Shijun Yuan
- Subjects
010302 applied physics ,Materials science ,Mössbauer effect ,Composite number ,Shell (structure) ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Oxygen ,lcsh:QC1-999 ,chemistry ,Chemical engineering ,0103 physical sciences ,Magnetic nanoparticles ,0210 nano-technology ,Mesoporous material ,Layer (electronics) ,lcsh:Physics ,Stoichiometry - Abstract
Fe3O4 particles with uniform size, regular shape and good dispersibility are prepared by solvothermal methods. The size of Fe3O4 particles and their magnetic properties can be adjusted during synthesis. Fe3O4@SiO2 composite magnetic particles with layers of mesoporous SiO2 structure are assembled by improved Stöber method. The different shell thickness of SiO2 layer can be adjusted from 35∼150 nm using multi-coating by changing the content of TEOS to form Fe3O4@nSiO2@mSiO2. The Mössbauer spectra show that Fe3O4 particles are almost stoichiometric. However, it is found that the coverage of SiO2 have a significant effect on the occupation of Fe ions in Fe3O4 particles. Peroxidation appears in Fe3O4@SiO2 composite magnetic particles, which might be caused by oxygen in SiO2 layer during wrapping process.
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- 2019
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32. Enhancing the Spin-Orbit Coupling in Fe
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Zhaocong, Huang, Wenqing, Liu, Jinjin, Yue, Qionghua, Zhou, Wen, Zhang, Yongxiong, Lu, Yunxia, Sui, Ya, Zhai, Qian, Chen, Shuai, Dong, Jinlan, Wang, Yongbing, Xu, and Baoping, Wang
- Abstract
By analyzing the in-plane angular dependence of ferromagnetic resonance linewidth, we show that the Gilbert damping constant in ultrathin Fe
- Published
- 2016
33. Study of Sm-doped ZnO samples sintered in a nitrogen atmosphere and deposited on n-Si(100) by evaporation technique
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Iain Will, Yongbing Xu, Muhammad Azhar Iqbal, Zhaocong Huang, and Ghulam Murtaza
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Materials science ,Scanning electron microscope ,Doping ,Analytical chemistry ,chemistry.chemical_element ,Substrate (electronics) ,Condensed Matter Physics ,Evaporation (deposition) ,Electronic, Optical and Magnetic Materials ,Samarium ,Paramagnetism ,chemistry ,Ferromagnetism ,Wurtzite crystal structure - Abstract
The samarium doping zinc oxide (Zn 1– x Sm x O) with ( x =0.0, 0.04, 0.05 and 0.17) polycrystalline thin films have been deposited on n-Si(1 0 0) substrate using thermal evaporation technique. Ceramic targets for deposition were prepared by the standard solid-state reaction method and sintered in nitrogen atmospheres. X-ray diffraction and scanning electron microscopy analyses show that the bulk and films features reveal wurtzite crystal structure with a preferential (1 0 1) crystallographic orientation and grows as hexagonal shape grains. According to the results of the Hall effect measurements, all the films show p-type conductivity, possibly a result of nitrogen incorporation into the Sm-doped ZnO samples. Magnetic measurements show that ferromagnetic behavior depends on the Sm 3+ concentration. For a film with lower Sm 2 O 3 contents ( x =0.04), a phenomenon of paramagnetism has been observed. While, with further increase of Sm 3+ contents ( x =0.05) the ferromagnetic behavior has been observed at room temperature. However, at higher doping content of Sm 3+ , the ferromagnetic behavior was suppressed. The decrease of ferromagnetism with increasing doping concentration demonstrates that ferromagnetism observed at room temperature is an intrinsic property of Zn 1– x Sm x O films.
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- 2011
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34. Reduction of In-Plane Uniaxial Magnetic Anisotropy in Patterned Single-Crystal Fe Dot Arrays
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Zhaocong Huang, Jing Wu, Ya Zhai, Daxin Niu, Yongbing Xu, Iain Will, X. Zou, and Ping Kwan Johnny Wong
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Materials science ,Kerr effect ,Condensed matter physics ,Magnetoresistance ,business.industry ,Magnetic hysteresis ,Focused ion beam ,Electronic, Optical and Magnetic Materials ,Crystal ,Magnetic anisotropy ,Optics ,Electrical and Electronic Engineering ,Thin film ,Anisotropy ,business - Abstract
Single-crystal Fe dot arrays with the lateral size varying from 400 nm to 50 nm are fabricated by focused ion beam (FIB) direct writing from a single-crystalline 10 monolayer (ML) Fe (100) continuous thin film grown on GaAs substrate. The Kerr hysteresis loops of both dot arrays and continuous thin film are measured by focused magnetooptical Kerr effect (MOKE) measurements along four major crystal directions: [0-11] [010] [011] and [001]. It is found that the in-plane uniaxial anisotropy has been greatly reduced down to zero in the dot arrays when the size is less than 150 nm. The micromagnetic simulations confirm the reduction of this intrinsic in-plane uniaxial anisotropy in the patterned dots by separating the effect of the shape anisotropy. The experimental and simulation results further indicate an additional magnetic uniaxial anisotropy along the [010] direction.
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- 2009
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35. The Shape Anisotropy in the Magnetic Field-Assisted Self-Assembly Chain-like Structure of Magnetite
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Litao Sun, H. R. Zhai, Yao-Zu Zhang, Zhaocong Huang, Xiaowan Bai, Yu Fu, Ya Zhai, and J. Du
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Materials science ,Magnetic domain ,Condensed matter physics ,Magnetometer ,Demagnetizing field ,Ferromagnetic resonance ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Magnetic field ,law.invention ,Condensed Matter::Materials Science ,Magnetization ,Magnetic anisotropy ,General Energy ,law ,Physical and Theoretical Chemistry ,Saturation (magnetic) - Abstract
A series of Fe3O4 particle chains with an average particle diameter of 150 nm and different lengths were synthesized by using the self-assembly method at reduced temperature in different synthesizing magnetic fields. The influence of synthesizing magnetic field on the properties of the magnetite particle chains was studied by structural analyses, magnetometry measurement, and ferromagnetic resonance. A uniaxial magnetic anisotropy in the saturation field (Hs), hysteresis loop, and ferromagnetic resonance were observed to increase with increasing synthesizing field. The saturation magnetization and g-factor were found to increase slightly with increasing synthesizing field. The demagnetizing fields and demagnetizing factors were determined from the experimental data of magnetometry measurement, ferromagnetic resonance, and also numerical calculation, which agreed reasonably well. It was found that the magnetization non-uniformity in the chains and the magnetostatic interaction among the chains have an impo...
- Published
- 2009
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36. Influence of Capping Layers on Magnetic Anisotropy in Fe/MgO/GaAs(100) Ultrathin Films
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Yu Fu, Yongbing Xu, Hongru Zhai, Wen Zhang, Zhaocong Huang, Ping Kwan Johnny Wong, Ya Zhai, and Yunxia Xu
- Subjects
Materials science ,Spintronics ,Condensed matter physics ,Magnetic structure ,Magnetoresistance ,Crystal structure ,Ferromagnetic resonance ,Electronic, Optical and Magnetic Materials ,Overlayer ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Condensed Matter::Superconductivity ,Electrical and Electronic Engineering ,Anisotropy - Abstract
Magnetic anisotropies of Fe/MgO/GaAs(100) hybrid structure with two different nonmagnetic capping materials, Au and MgO have been studied by ferromagnetic resonance (FMR). A uniaxial anisotropy, unexpected from the crystal structure was observed in the ultrathin films for both capping materials. Its global easy axis is along [0-11] direction while two (010) directions are equally magnetic hard regardless of the overlayer material. The in-plane uniaxial anisotropy (in-plane cubic anisotropy) of the Au capped samples is stronger (weaker) than that of the MgO capped ones within the range of t Fe = 7.1 to 28 ML. This suggests that the MgO overlayer suppresses the uniaxial anisotropy faster than the Au overlayer.
- Published
- 2008
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37. Enhancements of saturation magnetization and damping in Tb/Cr/Fe trilayers
- Author
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Li Sun, Ya Zhai, Hongru Zhai, Zhaocong Huang, Jun Du, Yunxia Sui, and Dong Zhang
- Subjects
Permalloy ,Magnetization ,Spin pumping ,Magnetic anisotropy ,Materials science ,Magnetic moment ,Condensed matter physics ,Ferromagnetism ,Magnetism ,Ferromagnetic resonance - Abstract
It is well-known that heavy Rare Earth (RE) metal of Tb, with stronger coupling of orbital and spin moments and anisotropic magnetism, can influence the magnetic properties of Fe based soft magnetism, especially tailor magnetization dynamic damping and in turn influence the magnetization switching time [1], [2], [3]. In our previous work, the dynamic damping of Fe-based films with dilute RE(Tb, Nd) dopants is indeed enhanced [4], [5], and even for the bilayers of Permalloy/ Nd(Tb), damping constant is increased strongly by spin pumping effect. However, the magnetic moments of Tb and TM are found to be antiferromagnetic coupling with each other, which reduces the net magnetic moment greatly. It is reported that the Tb film grown on the Fe layer, separated by ultrathin Cr layer can solve the problem based on the principle of RE-metal moments coupling antiferromagnetically with Cr, and Cr in turn coupling antiferromagnetically with Fe [1]. Hence, an effective ferromagnetic coupling is expected between the RE and the Fe magnetic moments to enhance the saturation magnetization, at the same time to remain a higher damping constant in the combination of RE/Cr/Fe multilayers.
- Published
- 2015
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38. Magnetocrystalline anisotropy in textured Fe3O4 film
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Jiafang Du, Yunxia Sui, Jinjin Yue, Ya Zhai, Hongru Zhai, Zhaocong Huang, Shaolong Tang, Er Liu, and Leyi Chen
- Subjects
Condensed Matter::Materials Science ,Magnetic anisotropy ,Materials science ,Exchange bias ,Magnetic domain ,Condensed matter physics ,Anisotropy energy ,Magnetic shape-memory alloy ,Condensed Matter::Superconductivity ,Anisotropy ,Magnetocrystalline anisotropy ,Magnetic susceptibility - Abstract
The magnetic anisotropies are one of the dominating factors affecting the behavior of magnetic materials, which is profoundly evident in magnetic ultrathin films, and significant in the application of information storage and magnetic sensor field. Extensive studies of magnetic anisotropies in various films have been carried out. It is well known that the contribution of magnetocrystalline anisotropy is negligible in isotropic polycrystalline films while essential in single-crystal films. However, in textured film, a polycrystalline film composed of nanograins with the near same lattice orientation, the competing interactions between magnetocrystalline and other anisotropy is still an open issue. The quantitative investigations on the contribution of magnetocrystalline anisotropy in the textured film are rarely reported. In this paper, the expression of magnetocrystalline anisotropy energy in textured film (texture anisotropy energy) is given, and angle-resolved FMR studies on the textured Fe 3 O 4 film is also presented.
- Published
- 2015
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39. Current-induced multiple domain wall motion modulated by magnetic pinning in zigzag shaped nanowires
- Author
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Yuli Yin, Philipp Dürrenfeld, Ya Zhai, Wen Zhang, Zhaocong Huang, Shuai Dong, and Xiaochao Zhou
- Subjects
Materials science ,Condensed matter physics ,Bar (music) ,Nanowire ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,lcsh:QC1-999 ,Magnetic anisotropy ,Zigzag ,0103 physical sciences ,Current (fluid) ,010306 general physics ,0210 nano-technology ,Anisotropy ,Micromagnetics ,Current density ,lcsh:Physics - Abstract
Using micromagnetic simulation, we investigate the current-induced multiple domain wall motion (CIDWM) in zigzag nanowires with different bar angles (θ=90°, 120° and 150°). Two dynamic processes of single DWM and double DWM are found in different regimes of current density identified by two thresholds in all zigzag nanowires. The decreasing threshold current is found in the zigzag nanowires with increased bar angles, indicating the angular-dependence of the magnetic pinning. This work suggests a possibility of manipulating the single/multiple DWM in future DW devices by introducing the shape anisotropy.
- Published
- 2017
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40. Growth and magnetic properties of ultrathin single crystal Fe3O4 film on InAs(100)
- Author
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Stuart Holmes, Yongbing Xu, Zhaocong Huang, Ya Zhai, Sarah Thompson, and Jing Wu
- Subjects
Materials science ,Kerr effect ,Condensed matter physics ,business.industry ,Annealing (metallurgy) ,Surfaces and Interfaces ,Condensed Matter Physics ,Magnetic hysteresis ,Epitaxy ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Magnetic anisotropy ,Semiconductor ,Optics ,chemistry ,Materials Chemistry ,Electrical and Electronic Engineering ,business ,Single crystal ,Magnetite - Abstract
Different thickness of ultrathin films of magnetite (Fe3O4) have been grown epitaxially on zinc-blende narrow band-gap semiconductor InAs(100) surfaces by in situ post-growth annealing of ultrathin epitaxial Fe films at 300 °C in an oxygen partial pressure of 5 × 10−5 mbar. Reflection high-energy electron-diffraction patterns show that the epitaxial Fe3O4 films have been rotated by 45° in-plane to match the InAs substrates. The magnetic hysteresis loops obtained by magneto-optic Kerr effect (MOKE) shows a in-plane uniaxial magnetic anisotropy for the ultrathin films, and the global easy axis is rotated from the uniaxial easy [011] direction to the cubic easy [010] direction when the thickness of the film increases.
- Published
- 2011
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41. Discontinuous properties of current-induced magnetic domain wall depinning
- Author
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Simon A. Morton, Jing Wu, Wen Zhang, Zhaocong Huang, Yongbing Xu, Li Chen, X. F. Hu, Daxin Niu, Iain Will, Andreas Scholl, G. van der Laan, Ya Zhai, and Rudong Zhang
- Subjects
Permalloy ,Multidisciplinary ,Materials science ,Condensed matter physics ,Spintronics ,Magnetic domain ,Magnetic circular dichroism ,Nanowire ,Article ,Condensed Matter::Materials Science ,Photoemission electron microscopy ,Piecewise ,Barkhausen stability criterion ,Simulation - Abstract
The current-induced motion of magnetic domain walls (DWs) confined to nanostructures is of great interest for fundamental studies as well as for technological applications in spintronic devices. Here, we present magnetic images showing the depinning properties of pulse-current-driven domain walls in well-shaped Permalloy nanowires obtained using photoemission electron microscopy combined with x-ray magnetic circular dichroism. In the vicinity of the threshold current density (Jth = 4.2 × 1011 A.m−2) for the DW motion, discontinuous DW depinning and motion have been observed as a sequence of “Barkhausen jumps”. A one-dimensional analytical model with a piecewise parabolic pinning potential has been introduced to reproduce the DW hopping between two nearest neighbour sites, which reveals the dynamical nature of the current-driven DW motion in the depinning regime.
- Published
- 2013
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42. Enhancement of magnetic moment in ZnxFe3−xO4 thin films with dilute Zn substitution
- Author
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Yuli Yin, Ya Zhai, Wen Zhang, Huiling Ou, Honglei Yuan, Zhaocong Huang, Hongru Zhai, P. K. Johnny Wong, Qingyu Xu, Er Liu, Jian-Guo Zheng, and Jun Du
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Magnetic moment ,Magnetometer ,Magnetic circular dichroism ,Doping ,Analytical chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Pulsed laser deposition ,Condensed Matter::Materials Science ,X-ray magnetic circular dichroism ,law ,Impurity ,Condensed Matter::Superconductivity ,0103 physical sciences ,Thin film ,010306 general physics ,0210 nano-technology - Abstract
Highly (111)-textured ZnxFe3−xO4 thin films were grown by pulsed laser deposition on silicon substrates. The spin and orbital magnetic moments of the ZnxFe3−xO4 thin films have been obtained by X-ray magnetic circular dichroism (XMCD) and sum rule analysis. The total magnetic moments thus extracted are in good agreement with the values obtained by vibrating sample magnetometer. Both the unquenched orbital moment and the ratio of orbital-to-spin moment first increase significantly with increasing Zn substitution at a low concentration range ( 0≤x≤0.1), and then decrease at a higher concentration (x = 0.3). The underlying site-specific doping mechanisms involved here have been elucidated by detailed analysis of the XMCD of ZnxFe3−xO4 films. Our work demonstrates a practical means to manipulate the spin-orbit coupling in the ZnxFe3−xO4 thin films via Zn impurity doping.
- Published
- 2016
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43. Magnetic property of ultrathin single crystal Fe3O4 film on InAs(100)
- Author
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Sarah Thompson, Jing Wu, Ya Zhai, Zhaocong Huang, and Yongbing Xu
- Subjects
Crystallography ,High energy ,Materials science ,Reflection high-energy electron diffraction ,Electron diffraction ,Ferromagnetism ,Annealing (metallurgy) ,business.industry ,Optoelectronics ,business ,Epitaxy ,Single crystal ,Molecular beam epitaxy - Abstract
In this paper, the epitaxial growth and the magnetic property of different thickness of ultrathin Fe3O4 film on InAs(100) are reported. As-capped InAs(100) substrate is loaded to the ultrahigh vacuum (UHV) molecular beam epitaxy (MBE) deposition chamber, following an annealing at 600° C for 30 minutes before growth. Then an in situ reflectance high energy electron diffraction (RHEED) patterns of InAs (100) substrate is conducted along its [011] axis.
- Published
- 2010
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44. Depinning behaviour of domain wall in magnetic nanowire with asymmetric notch
- Author
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Jialin Liao, Yongbing Xu, Bin Ma, Q. Y. Jin, Jing Wu, X. F. Hu, Zhaocong Huang, Wen Zhang, Zongzhi Zhang, and An Ding
- Subjects
Materials science ,Domain wall (magnetism) ,Condensed matter physics ,Field (physics) ,Nanowire ,Nucleation ,Physics::Optics ,Magnetic nanowires ,Ratchet effect ,Magnetic field ,Diode - Abstract
The magnetic nanowires have attracted great interests recently for their potential applications in novel logic and memory devices. The magnetization reversal of the magnetic nanowires is realized by the nucleation and the propagation of domain walls (DWs) along the wires. Both current and magnetic field driven DW motion have been proposed and investigated widely. One of the techniques to manipulate the DW is to introduce artificial defects to the nanowire structure such as different shapes of notches. Asymmetric notches have been reported to act as an asymmetric energy barrier for the DW and the depinning field and critical depin current depend on the direction of DW propagation, which is related to the slope of notch. The “Magnetic ratchet effect” has been addressed since the DW depins and moves easier in one direction than the other. Magnetic diodes were also proposed based on the asymmetric notch structure in magnetic nanowires. However, rather than constriction, the previous reports were based on the protruding shape of asymmetric notch. In this paper, we present a study on the depinning behaviour of the DW inside magnetic nanowires with a single inward asymmetric notch.
- Published
- 2010
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45. Direct magnetic imaging of domain wall manipulation in necked Permalloy wire using XPEEM
- Author
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Wen Zhang, Yongbing Xu, Huiqin Yang, K Xia, Jing Wu, G. van der Laan, Andreas Scholl, Chen Luo, Simon A. Morton, Zhaocong Huang, C Z Gu, Ping Kwan Johnny Wong, and Ya Zhai
- Subjects
Permalloy ,Photoemission electron microscopy ,Magnetization ,Materials science ,Domain wall (magnetism) ,Condensed matter physics ,Magnetic imaging ,Nanowire ,Photoelectron microscopy - Abstract
This paper presents the study using X-ray photoemission electron microscopy (XPEEM) of a simple and well defined single-layer necked Permalloy nanowire, which provides an artificial pinning site for domain wall. The XPEEM images provide direct evidence of the formation of the head-to-head or tail-to-tail domain wall by controlling the magnetization process.
- Published
- 2010
- Full Text
- View/download PDF
46. Texture induced magnetic anisotropy in Fe3O4 films
- Author
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Zhaocong Huang, Yunxia Sui, Ya Zhai, Jinjin Yue, Xiumei Wu, Jun Du, Er Liu, Hongru Zhai, Leyi Chen, Jian-Guo Zheng, and Shaolong Tang
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Anisotropy energy ,Ferromagnetic resonance ,Characterization (materials science) ,Condensed Matter::Materials Science ,Magnetic anisotropy ,Computer Science::Graphics ,Computer Science::Computer Vision and Pattern Recognition ,Condensed Matter::Superconductivity ,Texture (crystalline) ,Crystallite ,Thin film ,Anisotropy - Abstract
This letter reports a free energy density model for textured films in which the related physical concept and expression of magneto-texture anisotropy energy are presented. The structural characterization and out-of-plane angular dependence ferromagnetic resonance of strongly textured Fe3O4 films were systematically investigated. We found that the typical free energy density model for polycrystalline film cannot be applied to the textured films. With the introduction of magneto-texture anisotropy energy in the free energy density model for thin films, we simulated and quantitatively determined the competing anisotropies in (111)-textured Fe3O4 films.
- Published
- 2015
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47. The magnetic properties of well-aligned nickel nanochains synthesized by magnetic field-induced assembly approach
- Author
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Ya Zhai, Zhaocong Huang, Zhaoxia Kou, Yukun Wang, Hongru Zhai, Dong Zhang, Er Liu, Yunxia Sui, Jun Du, and Jinjin Yue
- Subjects
Condensed Matter::Materials Science ,Magnetic anisotropy ,Materials science ,Magnetic shape-memory alloy ,Magnetic domain ,Condensed matter physics ,Demagnetizing field ,General Physics and Astronomy ,Coercivity ,Magnetic hysteresis ,Ferromagnetic resonance ,Saturation (magnetic) - Abstract
Highly uniform one-dimensional Ni chains with controllable diameters and lengths have been synthesized at 70 °C by a hydrothermal process under a 0.35 T induced magnetic field. The diameter of the spheres in the magnetic Ni chains is adjusted from 80 nm to 1000 nm with the chain length changed from 1.2 μm to 50 μm by varying the concentration of ethylene glycol and potassium hydroxide in the solution. The Ni chains with different length-to-diameter aspect ratio show the different particle shape and interparticle spacing. Magnetic hysteresis loop measurements demonstrate a uniaxial magnetic anisotropy (UMA) on the coercivity (Hc), and saturation field (Hs). The ferromagnetic resonance (FMR) shows that the difference between demagnetizing fields in the direction of easy and hard increases with increasing the length-to-diameter aspect ratio of nanochains, which is close to then that in Hs. From FMR measurements and theoretical simulation, the difference of the demagnetizing field between the length and width...
- Published
- 2015
- Full Text
- View/download PDF
48. Investigation on transformation of spindle-like Fe3O4 nanoparticles from self-assembling α-Fe2O3
- Author
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Wen Zhang, Shijun Yuan, Zhaocong Huang, Ya Zhai, Baoping Wang, Hong Meng, Zhaoxia Kou, Hongru Zhai, Er Liu, and Dong Zhang
- Subjects
Materials science ,Annealing (metallurgy) ,Dispersity ,General Physics and Astronomy ,Nanoparticle ,Microstructure ,Hydrothermal circulation ,Nanomaterials ,symbols.namesake ,Crystallography ,Chemical engineering ,symbols ,Self-assembly ,Raman spectroscopy - Abstract
Porous monodisperse spindle-like α-Fe2O3 nanomaterials are first synthesized successfully by a hydrothermal method, and then the as-prepared nanoparticles are annealed at different temperatures under various atmospheres to achieve the spindle-like Fe3O4 nanoparticles. The evolution of the features of nanoparticles, including the changes of the structures and microstructures as well as the magnetic properties, during the reduction process has been investigated by using the Raman spectrum and Mossbauer spectrum. Our research reveals that the α-Fe2O3 nanoparticles annealed by covering of the C powder become a mixture of α-Fe2O3 and Fe3O4 in the range of annealing temperature from 300 °C to 800 °C. With reduced atmospheric H2, spindle-like α-Fe2O3 nanoparticles are transferred to mixture of α-Fe2O3, Fe3O4 and Fe as temperature increases. They are also converted from a typical rhombohedral structure to a cubic α-Fe phase at 500 °C. Finally, with the atmosphere of H2/Ar (5%/95%), a pure Fe3O4 phase, and its exc...
- Published
- 2015
- Full Text
- View/download PDF
49. Oxygen vacancy induced magnetization switching in Fe3O4 epitaxial ultrathin films on GaAs(100)
- Author
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Zhaocong Huang, Jinlan Wang, Baoping Wang, Yongbing Xu, Qian Chen, and Ya Zhai
- Subjects
Crystal ,Condensed Matter::Materials Science ,Magnetization ,Materials science ,Physics and Astronomy (miscellaneous) ,Magnetic moment ,Ferromagnetism ,Condensed matter physics ,Spintronics ,Magnetism ,Vacancy defect ,Thin film - Abstract
The magnetic and transport properties of half metallic Fe3O4, which are sensitive to the stoichiometry, are the key issue for applications in spintronics. An anomalous enlargement of the saturation magnetic moment is found in a relatively thick sample of epitaxial Fe3O4 film by post-growth oxidation method. The investigation of the thickness dependence of magnetic moment suggests that the enhanced magnetism moment may come from the existence of oxygen vacancies. First-principles calculations reveal that with oxygen vacancies in Fe3O4 crystal the spin of Fe ions in the tetrahedron site near the vacancy is much easier to switch parallel to the Fe ions in the octahedron site by temperature disturbance, supported by the temperature dependence of magnetic moment of Fe3O4 films in experiment.
- Published
- 2015
- Full Text
- View/download PDF
50. Demagnetizing factors in patterned CoNiFe films with rectangular elements
- Author
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Chen Luo, Yuli Yin, Ya Zhai, Yukun Wang, Dong Zhang, Yu Zhang, and Zhaocong Huang
- Subjects
Condensed Matter::Materials Science ,Materials science ,Condensed matter physics ,Condensed Matter::Other ,Demagnetizing field ,General Physics and Astronomy ,Anisotropy ,Ferromagnetic resonance ,Aspect ratio (image) ,Principal axis theorem - Abstract
CoNiFe patterned films with rectangular elements, all 600-nm wide but of different lengths, were fabricated and investigated by ferromagnetic resonance experiment and micromagnetic simulation. An in-plane magnetic uniaxial anisotropy was exhibited, and its value increases with the increase of the aspect ratio of the elements, which was fitted by the model, including a quasi-ellipsoid demagnetizing field and a non-uniform demagnetizing field. The relative importance of the non-uniform demagnetizing field decreased from 0.26 to 0.16 with the increase of the length—width aspect ratio of the patterned element from 1.5 to 10. The demagnetizing factors in the three principal axes were determined from the experimental data of ferromagnetic resonance, which agreed reasonably well with the values calculated by micromagnetic simulation. The calculation also indicated that the interaction between elements could be neglected when the edge-to-edge spacing between neighboring elements was larger than 3 μm in our patterned films.
- Published
- 2013
- Full Text
- View/download PDF
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