FeCuNbSiB单层膜和三明治膜的磁特性与巨磁阻抗效应

用射频溅射法制备了Fe_73.5Cu₁Nb₃Si_13.5B₉单层膜和 Cu或Ag作为中间层的三明治膜.溅态膜为非晶态结构.磁畴观察结果表明,单层膜在380℃退火后,呈现均匀磁化的纳米晶结构,该样品软磁特性最佳,其巨磁阻抗效应最大,在13MHz,最大磁阻抗比纵向为18％,横向为14％.溅态三明治膜具有较大的巨磁阻抗效应,在13MHz,Cu夹层三明治膜的最大磁阻抗比纵向为32％,横向为11％,Ag夹层三明治膜的最大磁阻抗比纵向为47％,横向为57％.Cu夹层三明治膜经250℃退火后,在低频下表现为巨磁电感效应,在100kHz,最大磁电感比为1733％. 关键词：     

FeCuCrVSiB单层和多层膜的横向巨磁阻抗效应

用射频溅射法制备了Fe_71.5Cu₁Cr_2.5V₄Si₁₂B₉单层膜和结构为(F/S)₃/M/(F/S)₃的多层膜，在制备过程中加72kA/m的纵向磁场.研究表明在制备过程中加磁场明显改善了材料的软磁性能，降低了材料的矫顽力.将样品经不同温度退火热处理后，发现经230℃退火1.5h的单层膜和多层膜具有最佳的软磁性能和最大的磁阻抗效应，单层膜最大横向磁阻抗比为37.5%，多层膜最大横向磁阻抗比高达277%.通过比较单层和多层膜磁阻抗效应随频率和磁场的变化，发现多层膜具有较低的磁阻抗效应的临界频率和峰值特征频率，和较大的磁阻抗变化率，而且有较低的横向磁阻抗效应的饱和场. 关键词： 铁基合金 多层膜 巨磁阻抗效应     

FeCuCrVSiB多层膜巨磁阻抗效应的研究

研究了结构为 (FM/SiO₂)₃/Ag/(SiO₂/FM)₃ 多层膜的巨磁阻抗(GMI)效应（这里的F M≡FeCuCrVSiB）．多层膜采用射频溅射法沉积在单晶Si衬底上，沉积过程中，沿膜面长方 向施加约72kA/m的磁场，然后在不同的温度下对样品进行了退火处理．结果表明，该多层膜 样品即使在沉积态便具有相当好的软磁性能和GMI效应，在7MHz的频率下，最大纵向和横向 巨磁阻抗比分别为45%和44%．在230℃下经90min退火处理后的样品具有最佳的GMI效应，在85MHz的频率下，最大纵向和横向巨磁阻抗比分别达到251%和277%．与磁性层总厚度相同的FeCuCrVSiB/Ag/FeCuCrVSiB三层膜相比较，在这种多层结构中出现的GMI效应更强． 关键词： 多层膜 巨磁阻抗效应 趋肤效应 有效磁导率     

磁场退火对Co基熔体抽拉丝巨磁阻抗效应的影响

对Co基熔体抽拉非晶丝进行了普通炉内退火和不同磁场强度（500 Oe,1600 Oe,4000 Oe）下的横向和纵向磁场退火,利用HP4192阻抗分析仪和Lakeshore7407VSM分析了退火态样品的巨磁阻抗（GMI）效应和软磁性能.研究结果表明,纵向磁场降低了环向各向异性,纵向磁场退火样品GMI效应降低且GMI曲线为单峰,最大阻抗变化率ΔZ/Z为131%,磁场响应灵敏度为7%/Oe;而横向磁场提高了环向畴体积,增加了环向各向异性场,导致退火样品GMI曲线随频率升高由单峰转 关键词： 非晶丝 巨磁阻抗效应 退火     

LC共振型巨磁阻抗效应的研究

采用化学镀方法成功制备了自带电容构成LC共振回路的CoP/Insulator/BeCu复合结构丝. 研究了这种新型复合结构丝产生LC共振型巨磁阻抗效应的特征,长度为l_m=95 cm的复合结构丝,当驱动电流频率为LC共振频率f_r=290 MHz时,LC共振型巨磁阻抗效应为4875%,磁场灵敏度为046%/A·m^-1,大于常规复合结构丝;远离此频率时的巨 关键词： 复合结构丝 LC共振')" href="#">LC共振 等效电路模型 巨磁阻抗效应     

铁磁/非铁磁/铁磁层状薄膜的巨磁阻抗效应的计算

基于文献[17]和[18]提出的铁磁非铁磁铁磁层状薄膜的电磁模型,详细研究了层状薄膜的巨磁阻抗增强效应,以及磁性层和非磁性层厚度与层状薄膜的巨磁阻抗效应的关系.分析表明,铁磁层和非铁磁层薄膜的电阻率相差越大,越有利于获得显著的巨磁阻抗效应;对于总厚度要求一定的层状薄膜,铁磁层和非铁磁层薄膜存在一最佳厚度 关键词： 巨磁阻抗效应 磁性薄膜 趋肤效应     

非晶CoFeNiNbSiB合金的巨磁阻抗效应

研究了非晶Co₇₀Fe_4.5Ni₄Nb₁Si_12.5B₈合金薄带的巨磁阻抗效应.实验表明,在一定频率范围内提高测试频率,磁阻抗效应有明显提高;适当温度的退火也有助于磁阻抗效应的提高.制备态非晶合金样品在频率为5MHz下达120%左右,经过退火处理的非晶样品5MHz下的效应可达400%左右. 关键词：     

三明治结构与同轴电缆结构磁性材料巨磁阻抗效应的理论研究

根据两种具有巨磁阻抗（GMI）效应的磁性材料实验样品，提出了两种理论模型（同轴电缆结构——Cu丝外覆软磁材料的圆柱形；三明治结构——Cu或Ag为中间层外包软磁层的三明治膜），利用Maxwell方程和Landau_Lifshitz方程对其GMI效应的机理进行了理论研究.证明了两种模型的差别仅仅是形状因子的不同，从而由理论上证实了两种结构GMI效应增强的内在一致性.证实了在同种磁性材料情况下，双层结构具有结构方面的优越性.并对照实验数据讨论了参数的影响，得到与实验定性相符的结果. 关键词： 巨磁阻抗效应 三明治膜 Maxwell方程 Landau_Lifshit     

介观结构对纳米晶软磁合金巨磁阻抗效应影响的理论分析

根据用原子力显微镜对Fe基纳米晶Fe_73.5Cu₁Nb₃Si_13.5B₉合金薄带的介观结构和巨磁阻抗效应的实验研究结果，提出了纳米晶软磁合金巨磁阻抗效应受其介观结构影响的理论模型.该模型成功地解释了低频对纳米晶软磁合金巨磁阻抗效应的影响，反映了现有“三明治”理论的主要特征，并弥补了它的不足；同时指出了纳米晶粒电导率σ、磁导率μ对合金巨磁阻抗效应有影响. 关键词： 铁基纳米晶合金 介观结构 巨磁阻抗效应 介观模型     

电流退火铁基薄带巨磁阻抗效应的影响

研究了电流退火工艺对铁基非晶合金Fe₈₄Zr₈Nb_3.5B_3.5Cu_{1〈/sub>薄带巨磁阻抗效应的影响.实验结果表明,该铁基合金的巨磁阻抗ΔZ/Z随退火电流的增加而增强,当电流为820mA时,ΔZ/Z达到最大值62％,阻抗变化灵敏度可达约0.23％（A/m)^-1.结合此合金在电流退火燧后电性能和软磁性能的演变,讨论了材料的巨磁阻抗效应借助趋肤效应与交流频率和外加纵向磁场的关系. 关键词：}     

电沉积复合丝及其巨磁阻抗效应的研究

采用脉冲电沉积工艺在Cu丝上沉积Fe Ni合金镀层 ,成功地制备出巨磁阻抗效应 (GMI)复合丝材料 ,研究了复合丝的磁性能和巨磁阻抗效应 .复合丝外壳磁性镀层软磁性越好 ,巨磁阻抗效应越明显 ,制备的复合丝最高巨磁阻抗效应为 2 7.19% .研究了复合丝阻抗与巨磁阻抗比值GMI随外加磁场的变化 ,其变化曲线的形状受复合丝磁各向异性场的影响 .此外 ,还研究了复合丝巨磁阻抗效应与驱动交变电流频率的关系 ,复合丝Fe17Ni83 样品巨磁阻抗效应的临界频率为 30kHz(GMI为 9.95 % ) ,特征频率为 30 0kHz(GMI为 2 7.19% ) ,截止频率为 10MHz (GMI为 10 .36 % ) .如此低的临界频率和特征频率及较宽的频率段对于实际应用非常有利 .     

Giant magneto-impedance effect of magnetron sputtered Ni80Fe20/SiO2/Cu composite wires

In this work, Ni₈₀Fe₂₀/Cu and Ni₈₀Fe₂₀/SiO₂/Cu composite wires of Cu core 100 μm in diameter and coated with a layer of Ni₈₀Fe₂₀ were produced by RF magnetron sputtering. In order to obtain a uniform coating, the wires were spun during sputtering. The influences of the magnetic coating and insulator thickness on the GMI effect of the composite wires were investigated. The results showed that the film thickness has a significant effect on the magnitude and the optimum frequency of the GMI effect. After the addition of an insulator layer, the MI ratio of the composite wires was observed to change with varying thickness of the insulator layer. This observed trend was attributed to the interaction between the conductive layer and the high-permeability magnetic coating.     

Sputtered amorphous Co-Pt-P thin films for soft underlayer of perpendicular magnetic recording

In this paper, a novel amorphous Co-Pt-P thin film fabricated by DC sputtering was proposed for soft underlayer in perpendicular recording. The structural and magnetic properties of the films were investigated by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. The results show that maximum permeability of Co-12 at%Pt-P films sputtered at room temperature (RT) is quite low when the phosphorus content is less than 5.2 at%, but Co-12 at%Pt-7 at%P thin film, is of amorphous state and has a high permeability of ∼500. The excellent soft magnetic properties of maximum permeability (500), coercivity (18 Oe) and saturation magnetization (760 emu/cm³) indicate that the amorphous Co-12 at%Pt-7 at%P film is expected to be a promising soft magnetic underlayer of perpendicular magnetic recording. The Co-12 at%Pt-7 at%P thin film is gradually crystallized with increasing substrate temperatures. The crystallization temperature of the Co-12 at%Pt-7 at%P thin film is ∼200 °C.     

Giant magnetoimpedance in amorphous (Co0.93Fe0.7)63Ni10Si11B16 glass-coated microwire

Giant magnetoimpedance (GMI) effect has been measured in a glass-coated amorphous (Co_0.93Fe_0.7)₆₃Ni₁₀Si₁₁B₁₆ microwire as a function of DC magnetic field and up to the frequency of 11 MHz. The sample shows single peak GMI characteristics within the whole range of frequency. The domain structure of the above sample has been changed by applying tensile stresses up to 603 MPa and current annealing with a DC current of 50 mA for various time durations, and the corresponding effect on GMI has been studied in detail. A maximum change of 8.85% in MI of the as-quenched sample has been observed around a frequency of 5.05 MHz. Application of an external tensile stress reduces the GMI value by increasing the inner core domain, whereas heat treatment of the sample enhances the same. The square-shaped magnetic hysteresis loop of the as-quenched sample helps us understanding the MI results.     

SERS activity of silver and gold nanostructured thin films deposited by pulsed laser ablation

The deposition power dependence of visible transmittance and refractive index of room temperature-deposited ZnO:Al thin films by RF magnetron sputtering has been studied. All films exhibited high visible transmittance and near-complete UV absorption. The refractive index of the films decreased continuously with an increase in the RF power at all photon energies in the visible and near-IR region, which has been partially attributed to the decreased packing density of the films. For each film, the refractive index exhibited strong frequency dispersion in the weak-absorption region. The origin of optical dispersion at different RF power has been discussed in the light of a single-oscillator model.     

Magnetic and Mössbauer studies of Fe/Mo multilayered thin films

Fe(x)/Mo(y), multilayered thin films (MLF) with y=7.0 nm and x=0.7, 1.3, 2.6, 3.6, 13.0 nm were fabricated by radio frequency (RF) sputtering. X-ray diffraction evidences that these films have a good periodicity and bcc structure for both Fe and Mo layers. Mössbauer spectra at room temperature (RT) are used to investigate the structure and the local magnetic properties of the interfaces between Fe and Mo layers. It is found that the interfaces present alloying features, i.e. the Fe atoms are randomly substituted by Mo atoms. Magnetic anisotropy which forces magnetic moments to lie in the film plane and reduced magnetic moments in interface region were observed. The specific magnetization of the films exhibits a BT^3/2 dependence with very large values of B which can be attributed to the distribution of exchange interaction in the interfaces.