共查询到20条相似文献,搜索用时 140 毫秒
1.
《电子元件与材料》2016,(9):33-36
采用电化学沉积法封装阳极氧化铝(AAO)模板,制备出不同直径的Fe纳米线阵列。Fe纳米线阵列的形貌、组成、晶型、磁学性能分别通过场发射扫描电子显微镜(SEM)、X-射线能谱仪(EDS)、X-射线衍射仪(XRD)、震动样品磁强计(VSM)进行表征。结果表明:电化学沉积法可以制备出直径为33~95 nm的Fe纳米线;纳米线排列有序,粗细均匀,具有明显的[110]择优取向。VSM测试结果表明纳米线的直径对其磁性能影响很大。当纳米线直径为33~40 nm时,纳米线具有明显的磁各向异性,垂直模板表面的方向为易磁化方向,该方向上矫顽力达112 745.4 A/m以上,矩形比达0.43以上;当纳米纤维直径为75~95 nm时,纳米线的磁各向异性较弱,轴向上矫顽力和矩形比也较小。 相似文献
2.
矩形波导有限相控阵单元的阵中特性 总被引:1,自引:0,他引:1
利用矩时法对以矩形开口波辐射单元的有限相控的单元阵中方向图及口面磁流分布进行了计算。讨论了不同位置开口波导在不同扫描角时互耦对口面分布的影响。 相似文献
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对 Gd Fe Co/Al N/Dy Fe Co静磁耦合多层薄膜变温磁化方向变化进行了研究。结果表明读出层 Gd Fe Co随温度上升从平面磁化转变成垂直磁化 ,转变过程中受饱和磁化强度 (Ms)和有效各向异性常数影响 ,但主要受饱和磁化强度 (Ms)的影响。在高温时读出层的磁化强度很小 ,退磁场能减小 ,在静磁耦合作用下 ,使 Gd Fe Co读出层的磁化方向发生转变 ,而且磁化方向的转变在较小的温度范围内变化较快。 相似文献
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本文采用磁力显微镜(MFM)对磁性石榴石(YGdBi)3(GaFe)5O12薄膜的磁畴结构进行了观察研究。实验结果表明,磁性针尖的磁特性进行对石榴石MFM图像的影响较大,而且随着针尖与样品间距的增大,磁针尖对石榴石畴结构的影响有所降低。另外,改变针尖的磁化方向,得到的石榴石磁畴结构也有所不同。 相似文献
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采用组合靶,利用磁控共溅射技术制备了Co1-xPtx:C复合纳米颗粒薄膜,并从实验和理论上对不同Pt浓度CoPt:C薄膜的组分、微结构、磁性能、组分和微结构与磁性能之间的关系以及薄膜的应用进行了初步研究。发现CoPt粒子取向和磁性能与CoPt:C薄膜中的Pt浓度有密切关系,在较高Pt浓度的CoPt:C薄膜中观察到垂直各向异性现象。通过改变Pt浓度,可以获得粒子粒径小于10nm、矫顽力可控、垂直磁晶各向异性较高的薄膜。晶格结构和晶粒之间的作用力可认为是影响CoPt:C薄膜磁性能的主要因素。 相似文献
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基于提出的光学读出非制冷红外成像系统,先后制作了不同单元尺寸的单层膜无基底焦平面阵列(FPA),获得了室温物体的热图像。分析发现,当FPA的单元尺寸从200μm逐渐减小到60μm时,基于恒温基底模型的理论响应与实验结果的偏差逐渐增大。通过有限元方法,模拟分析了不同尺寸的微梁单元在无基底FPA中的热学行为,发现了当单元尺寸逐渐减小时,恒温基底模型偏差逐渐增大的原因,即无基底FPA的支撑框架逐渐不满足恒温基底条件,受热辐射后,支撑框架的温升从基底上抬高了单元的温升。论文还分析了无基底FPA的红外成像性能。当单元尺寸为60μm时,其热探测灵敏度比传统的有基底FPA高一个数量级。 相似文献
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波导端头裂缝有限相控阵单元的阵中特性 总被引:1,自引:0,他引:1
本文利用矩量法对以矩形波导端头裂缝为辐射单元的有限相控阵的单元阵中方向图及口面磁流分布进行了计算,讨论了不同位置辐射单元在不同扫描角时互耦对口面分布的影响。 相似文献
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A. V. Goryachev M. Yu. Chinenkov N. A. Dyuzhev A. M. Mednikov A. F. Popkov F. A. Pudonin 《Semiconductors》2009,43(13):1695-1699
The effect of the geometric shape of elements of a spin-dependent tunneling gate on their magnetic characteristic is studied
theoretically and experimentally. The hysteresis dependences of the magnetization and magnetoresistance of rectangular, hexagonal,
and ringed elements on the magnetic field are calculated for different characteristically geometric parameters of the elements.
In the studies of the magneto-optical Kerr effect, magnetic hysteresis loops are observed. The calculated and experimental
magnetization curves are compared, and qualitative agreement between the curves is gained. 相似文献
12.
利用微磁学方法系统研究了纳米尺度的NiFe薄膜菱形单元的自发磁化状态及剩磁状态。研究结果表明,在不同的尺寸下,菱形单元将有不同的自发磁化状态及剩磁状态。在单元的长宽尺寸小于某个临界尺寸时,菱形单元结构呈现单畴态。同时还分析了菱形NiFe单元作为磁性随机存储器(MRAM)存储单元时的要求。 相似文献
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Zuwei Liu Pai‐Chun Chang Chia‐Chi Chang Evgeniy Galaktionov Gerd Bergmann Jia G. Lu 《Advanced functional materials》2008,18(10):1573-1578
Ferromagnetic cobalt nanowires with high‐crystalline quality are synthesized using a low‐voltage electrodeposition method. High‐resolution transmission electron microscopy (HRTEM) and X‐ray diffraction (XRD) results show that the nanowires are uniform in size, and consist of predominantly hexagonal close‐packed (hcp) structure with the magnetocrystalline easy axis (c‐axis) perpendicular to the wire axis. Superconducting quantum interference device (SQUID) measurements illustrate the dominance of shape anisotropy, manifested by the weak temperature dependence of the enhanced coercive field along the wire axis. Furthermore, the magnetic structures of individual, segmented, or intersected nanowires are studied using magnetic force microscopy. This reveals a strong dipole at the two ends of the wire, together with a spatial magnetization modulation along the wire. Based on theoretical modeling, such intrinsic modulation is attributed to magnetization frustration due to the competition between the magnetocrystalline polarization along the easy axis and the shape anisotropy along the wire axis. 相似文献
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Local Writing of Exchange Biased Domains in a Heterostructure of Co/Pd Pinned by Magnetoelectric Chromia 下载免费PDF全文
Uday Singh W. Echtenkamp M. Street Ch. Binek S. Adenwalla 《Advanced functional materials》2016,26(41):7470-7478
The writing of micrometer‐scaled exchange bias domains by local, laser heating of a thin‐film heterostructure consisting of a perpendicular anisotropic ferromagnetic Co/Pd multilayer and a (0001) oriented film of the magnetoelectric antiferromagnet Cr2O3 (chromia) is reported. Exchange coupling between chromia's boundary magnetization and the ferromagnet leads to perpendicular exchange bias. Focused scanning magneto‐optical Kerr measurements are used to measure local hysteresis loops and create a map of the exchange bias distribution as a function of the local boundary magnetization imprinted in the antiferromagnetic pinning layer on field cooling. The robust boundary magnetization of the Cr2O3 fundamentally alters the exchange bias mechanism, enabling the writing of micrometer‐scaled regions of oppositely directed exchange bias using a focused laser beam. 相似文献
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Space-tapered circular (ring) array 总被引:1,自引:0,他引:1
This paper describes how the space-tampered linear array, designed to achieve a given linear distribution, can be extended to circular arrays. In linear array, Taylor distribution and uniform-amplitude array elements is used to approximate it. Spacing of the element is done so that the width associated with each element matches the scaled integral of the distribution along the same length. Each array element samples half spacing on each side. 相似文献
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Radiation scattered from diffraction gratings on the surface of waveguides is analyzed using the volume current method. This technique allows the interpretation of the grating elements as scattering centers of the underlying waveguide mode, and radiating sources for the diffracted fields. The framework allows separation of the effects of the grating array global periodicity and the effects of the specific shape of the individual grating elements. A straightforward analogy between the effects of the grating element shape and the behavior of phased-antenna array systems allows a clear and intuitive understanding of the effects of blazed gratings on the directionality of grating-coupled radiation. The analysis is applied to some specific geometries. 相似文献
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The ldquoplane wave spectral techniquerdquo is used to investigate theoretically the extent of mutual coupling between two box-horn elements of a phased array terminated in three-layered bio-media (skin, fat, and muscle layers). The results obtained have been validated against published results in the literature. Each box-horn of the array is assumed to be filled with water to provide good impedance match to the bio-media. Also, it reduces the dimensions of each box-horn which makes it suitable for array configuration. The effects of relative position of elements, spacing between elements, frequency, aperture size of each element, relative phase and amplitude of excitation of the elements on mutual coupling coefficients are numerically investigated and presented for an array of two box-horns terminated in bio-media. The specific absorption rate (SAR) distributions along the direction of the array axis in muscle layer of the bio-media in direct contact with a collinear array of two box-horns both with and without mutual coupling considerations are also computed and presented. The results of the present research work can provide useful design guidelines for the development of prototypes of box-horn array for hyperthermia treatment of tumors. Bio-media, box-horn, hyperthermia, mutual coupling, phased array, plane wave spectra. 相似文献
19.
L. A. Fomin I. V. Malikov V. Yu. Vinnichenko G. M. Mikhailov 《Russian Microelectronics》2008,37(5):283-295
A magnetic-force-microscopy investigation is conducted into the influence of the shape and magnetic anisotropy on the magnetic structure and the mode of magnetization reorientation in epitaxial iron thin films patterned by subtractive techniques. Magnetic anisotropy is found to have a strong influence on the magnetic structure. With an applied field directed along a specimen, the latter is in a single-domain state when oriented parallel to the easy axis of magnetization, and is in a multidomain state when oriented perpendicular to the easy axis, the domain magnetic moments being parallel to the easy axis in both cases. The magnetic structure appears as a streaky pattern. Magnetization reorientation proceeds by domain-wall motion in both cases. The tanks do not change the mechanism of magnetization reorientation in the rectangular part, yet they ensure a single-domain state at lower magnetic flux densities. The results should offer some scope for using epitaxial iron thin films of suitable shape and crystallographic orientation in spin-valve injectors or detectors. 相似文献
20.
The theory and experimental results are presented for an electronically scanned array antenna using multiple wavelength ferrite aperture elements at millimeter wavelengths. The theory for the individual element scanner is given, along with the experimental patterns. Curves showing the tradeoffs of aperture size, scan capability, and efficiency are plotted for the element scanners. A five-element array employing the element scanner as elements was analyzed, constructed, and tested experimentally. The constructed array scanned50deg (pm25deg )with a scan speed of 50 milliseconds. 相似文献