超磁致伸缩薄膜研究进展

综述了近几年国内外超磁致伸缩单层膜、多层膜的研究进展;介绍了超磁致伸缩薄膜的制备方法与性能表征;论述了TbDyFe单层薄膜的磁致伸缩和磁学性能以及其成分、应力、热处理、衬底温度等性能的影响因素;详述了超磁致伸缩多层膜组成和结构类型;讨论了热处理、磁场诱导和单层膜厚对多层膜在低场下磁致伸缩和磁学性能的影响,评述和展望了超磁致伸缩薄膜的国内外研发应用现状和发展趋势.     

TbFe/Fe交换耦合磁致伸缩多层膜的制备

采用双靶磁控溅射法制备了 TbFe/Fe交换耦合磁致伸缩多层膜,考察了热处理时间、Fe层厚度、溅射功率以及Ar气分压对多层膜低场磁致伸缩性能的影响。研究结果表明:TbFe 磁致伸缩层与软磁 Fe层之间通过交换耦合作用以及热处理能明显提高薄膜的软磁性能和磁致伸缩性能;TbFe/Fe多层膜的磁致伸缩性能对热处理时间、Fe 层厚度、溅射功率、Ar 气分压等薄膜沉积参数十分敏感;与 TbFe 磁致伸缩薄膜相比TbFe/Fe交换耦合磁致伸缩多层膜水平方向的矫顽力从 16kA/m降低到 9.6 kA/m。在外加磁场为8000 A/m条件下,TbFe/Fe磁致伸缩多层膜最大磁致伸缩系数可达1.58×10-4。     

热处理温度对TbFe2/Fe交换耦合磁致伸缩多层膜的影响

采用直流磁控溅射在20mm×5mm×240μm抛光单晶硅片上制备了TbFe2/Fe磁致伸缩多层膜,主要研究了热处理温度对TbFe2/Fe磁致伸缩多层膜磁致伸缩系数的影响.采用量热分析法(DSC)、XPS以及光杠杆测试法对TbFe2/Fe磁致伸缩多层膜的晶化曲线、成分随深度的变化以及磁致伸缩系数进行了分析与测试.结果表明TbFe2薄膜的起始晶化温度为327℃,晶化温度为372℃;TbFe2/Fe磁致伸缩多层膜的最佳热处理温度为327℃,在此热处理温度下热处理60min,外加磁场1.6×104A/m时,TbFe2/Fe磁致伸缩多层膜磁致伸缩系数可达1.56×10-4.采用XPS分析了一个周期的TbFe2/Fe成分随薄膜深度的变化,未经热处理的薄膜Fe层和TbFe2层之间界面清晰,两层之间有少量的扩散.经327℃热处理60min的薄膜Fe层和TbFe2层界面发生了互扩散,原子数之比也发生了改变.     

热处理对Tb0.27Dy0.73Fe2巨磁致伸缩薄膜性能的影响

本文研究了热处理对Tb0.27Dy 0.73Fe2薄膜磁性及巨磁致伸缩性能的影响.XRD分析表明制备态的Tb0.27Dy 0.73Fe2薄膜为非晶态,并且在450℃退火仍然保持非晶态,制备态的Tb0.27 Dy0.73Fe2薄膜显示垂直磁各向异性,在退火后向平行磁各向异性变化.热处理提高了Tb0.27Dy0.73Fe2薄膜在低磁场下的磁致伸缩特性.     

磁弹性型磁致伸缩多层膜的研究与开发

本文介绍了近年来对磁弹性型磁致伸缩多层膜的研究与开发，论述了研究过程中所探索出的一些多层膜的制备理论；探讨了包括多层膜的靶材选择、单层膜厚、层数、组织结构和真空热处理对其性能的影响。     

超磁致伸缩多层悬臂梁的场致弯曲

利用四参量模型系统研究了由超磁致伸缩（GMS）薄膜材料制备的多层悬臂梁的弯曲问题，其中包括GMS/NMS（非磁衬底）、GMS/GMS、GMS/NMS，GMS等悬臂梁体系．针对此3类悬臂梁研究了它们的弯曲挠度等弯曲特性与构成悬臂梁的各种参数的关系，为进一步设计和优化新型悬臂梁体系给出了一些建议性结论．计算结果表明，GMS/GMS双层悬臂梁，其挠度最大值总是大于具有相同几何结构的其它悬臂梁体系。当在悬臂梁系统中需要使用非磁衬底时，较软而且较薄的衬底有益于得到更大的弯曲挠度，相比之下，两层薄膜较硬，因此薄膜不宜过厚．两层磁致伸缩材料的最优厚度比主要由两层材料的弹性模量比决定，即较软的薄膜需有较大的厚度。由于弯曲后悬臂梁自由端位移向下．因此较硬的磁致伸缩薄膜2（沉积在衬底下表面上的薄膜）有益于增加GMS/NMS/GMS3层悬臂梁的挠度．     

热处理对Tb0.27Dy0.73Fe2巨磁致伸缩薄膜性能的影响

本文研究了热处理对Tb0.27Dy0.73Fe2薄膜磁性及巨磁致伸缩性能的影响。XRD分析表明制备态的Tb0.27Dy0.73Fe薄膜为非晶态,并且在450℃退火仍然保持非晶态,制备态的Tb0.27Dy0.73Fe2薄膜显示垂直磁各向异性,在退火后向平行磁各向异性变化。热处理提高了Tb0.27Dy0.73Fe2薄膜在低磁场下的磁致伸缩特性。     

超硬纳米多层膜致硬机理研究

本文综述了近年来纳米多层膜界面微结构及超硬效应的研究进展, 表明纳米多层膜硬化的主要机制和位错的运动相关, 晶格错配引起的交变应变场对硬化起次要作用, 模量差异致硬起主要作用. 指出了超硬纳米多层膜研究所存在的问题以及未来的发展方向.     

Tb0.4Dy0.6(Fe1-xMnx)1.91(x=0,0.05,0.1 0,0.15)合金的磁致伸缩性能

研究了Mn替代Fe对多晶Tb0.4Dy0.6Fe1.91合金棒材性能的影响.分析了Tb0.4Dy0.6(Fe1-xMnx)1.91(x=0,0.05,0.10,0.15)多晶棒材的结构、晶格常数、居里温度和磁致伸缩性能,发现Mn替代Fe后,样品仍然为MgCu2型Laves相结构.随着Mn含量从0增加到0.15,样品的晶格常数从7.335A增加到7.347A,居里温度从668K降低到526K.Mn原子的替代通过改变材料的交换相互作用、总磁矩和易磁化方向影响材料的磁致伸缩性能.实验结果显示,Tb0.4Dy0.6(Fe1-xMnx)1.91样品在石=0.10时综合性能最好.     

衍射法X射线激光分束光栅平行度测量系统(英文)

介绍了软X射线光栅分束镜Mach-Zehnder干涉等离子体诊断系统调整用双频光栅线条平行度的衍射法测量系统.该系统主要由激光器,准直镜,待测光栅,精密转台(含角度测量仪),直线工作台,光栅调节架和探测器组成.分析了系统中各种误差对测量精度的影响其中包括距离测量误差、波长误差、光栅准直误差即光栅刻线与入射光和反射光组成的平面不垂直、光栅转动过程的误差、光栅表面面型误差、探测器误差,经计算得到系统的绝对误差为minute.计算表明,该系统的测量精度满足软X射线Mach-Zehnder干涉系统对双频调整光栅的性能要求.     

Tb2Fe17-xCrx化合物的结构与磁性

通过X射线衍射及磁测量手段研究了Tb2Fe17-xCrx（x=0、0．5、1．0、1．5、2．0、3．0)化合物的结构与磁性。研究结果表明Tb2Fe17-xCrx化合物具有Th2Ni17型结构，随着Cr替代量x的增加，Tb2Fe17-xCrx化合物的单胞体积呈现非线性的减小，而晶胞参数a、c呈现复杂的变化。分析表明Tb2Fe17-xCrx化合物中存在着较强的磁一弹耦合效应。对磁性质的研究结果表明随着Cr替代量x的增加，Tb2Fe17-xCrx化合物的居里温度升高，在x=1．0时达到最大值，为539K，当Cr替代量x继续增加时，Tb2Fe17-xCrx化合物的居里温度下降。随着Cr替代量x的增加，Tb2Fe17-xCrx化合物的自发磁化强度急剧下降，分析表明在Tb2Fe17-xCrx化合物中，Cr的磁矩反平行于Fe的磁矩。     

Structural, magnetic and electrical properties of Fe/Cu/Fe films

A set of sandwich films in the configurations, Fe(200 nm)/Cu(t)/Fe(200 nm); t = 20 nm, 40 nm, 60 nm, 80 nm, 100 nm and 200 nm have been grown using thermal and electron beam gun evaporation techniques at a temperature of 473 K, under high vacuum conditions. The structure and crystallite sizes of the films were investigated by grazing incidence X-ray diffraction (GIXRD). The microstructure was examined by scanning electron microscope (SEM) studies. Average grain size and surface roughness were determined by atomic force microscope (AFM). The room temperature magnetization as a function of field has been measured using the vibrating sample magnetometer (VSM). The results revealed the existence of antiferromagnetic (AF) coupling between Fe layers through an interfacer Cu layer. The strength of AF coupling was observed to be increasing with increasing t and became maximum for t = 60 nm and, decreases for further increase in t. The behavior of coercive field with t indicated softness of the films. The low temperature electrical resistivity in the range from 4.2 K to 300 K has been measured. The residual resistance ratio, RRR and the temperature coefficient, TCR were determined. The power laws for the resistivity variation with temperature have been established. This is for the first time that a set of sandwich films in the present configurations were investigated for structural, magnetic and electrical properties and, the power laws for resistivity variation at low temperature have been established.     

树脂基稀土-铁系超磁致伸缩复合材料的磁致伸缩及其高频磁性能

以粉末粘结、模压成型方法,研制了0-3型的E-44环氧树脂基稀土-铁系超磁致伸缩复合材料。采用电阻应变片技术与Agilent 4294A型动态阻抗分析仪,研究了超磁致伸缩合金/环氧树脂复合材料的磁致伸缩性能及高频磁性能,并对所制备的磁致伸缩复合材料的磁导率、截止使用频率等随频率和树脂体积分数的变化规律进行了系统研究。结果表明:树脂的添加,不仅可以提高复合材料的截止频率和高频磁性能,使其具有良好的高频响应特性,其截止频率达30 MHz以上;而且通过适当选择树脂的体积分数,复合材料仍能保持良好的磁致伸缩性能,当树脂体积分数分别为20%、30%时,磁致伸缩系数分别达808×10-6、821×10-6,而当复合材料中树脂的体积分数为50%时,其磁致伸缩系数仍高达592×10-6。探讨了树脂/磁致伸缩复合材料的磁电耦合机制。      

Sensors development using its unusual properties of Fe/Co-based amorphous soft magnetic wire

In this paper, the unusual properties of amorphous soft magnetic wire with Fe-based or Co-based in compositions have been discussed: giant magnetoimpedance effect (GMI), giant stress-induced impedance effect, large Barkhausen effect, magnetostriction effect. Sensor operating principles and applications exploiting these unusual properties have also been discussed: magnetic field sensors, position sensors, biosensors, non-destructive testing sensors, stress sensors etc.     

Annealing behaviour and magnetic properties of Co/Pt and Fe/Pt bilayer thin films

The annealing behaviour and magnetic properties of Co/Pt and Fe/Pt bilayer thin films are investigated. The coercivity of Co/Pt bilayer thin films increases with annealing above 450 °C and shows a peak value of 40 kA m⁻¹ in the range from 500 to 550 °C. This increase is due to both the formation of a CoPt solid solution and the optimization of grain diameters. Furthermore, the increase is promoted by multilayering. Similar results were obtained for Fe/Pt bilayer thin films.     

Effect of substrate temperature on the structural and magnetic properties of Fe/Ag superlattices

In the present work, Fe/Ag superlattices were grown by molecular beam epitaxy (MBE) on MgO(001) single crystal substrates maintained at room temperature or at 423 K during the deposition. The structural properties were carried out using small and high angle X-ray diffraction techniques. The magnetic hysteresis loops with the magnetic field applied parallel or perpendicular to the plane of the films were measured by a superconducting quantum interference device (SQUID) magnetometer in the temperature range 5–300 K. A comparison of the obtained results showed that the heating of MgO substrates leads to a strong interdiffusion and causes a significant modification of structural and magnetic properties of Fe/Ag superlattices.     

Effect of substrate temperature on ac conduction properties of amorphous and polycrystalline GaSe thin films

X-ray diffraction analysis of GaSe thin films used in the present investigation showed that the as-deposited and the one deposited at higher substrate temperature are in amorphous and polycrystalline state, respectively. The alternating current (ac) conduction properties of thermally evaporated films of GaSe were studied ex situ employing symmetric aluminium ohmic electrodes in the frequency range of 120-10⁵ Hz at various temperature regimes. For the film deposited at elevated substrate temperature (573 K) the ac conductivity was found to increase with improvement of its crystalline structure. The ac conductivity (σ_ac) is found to be proportional to (ω^s) where s < 1. The temperature dependence of ac conductivity and the parameter, s, is reasonably well interpreted by the correlated barrier-hopping (CBH) model. The maximum barrier heights W_m calculated from ac conductivity measurements are compared with optical studies of our previous reported work for a-GaSe and poly-GaSe thin films. The distance between the localized centres (R), activation energy (ΔE_σ) and the number of sites per unit energy per unit volume N(E_F) at the Fermi level were evaluated for both a-GaSe and poly-GaSe thin films. Goswami and Goswami model has been invoked to explain the dependence of capacitance on frequency and temperature.