磁性薄膜及其复合结构高频特性研究进展

主要对国内外近年来在铁磁纳米薄膜及其复合结构的高频特性方面的最新研究成果做了较为系统的总结。从铁磁单层膜、复合多层膜、纳米薄膜对高频电磁场的响应机制和理论及计算模拟、薄膜高频电磁特性的测量技术几方面做了分析和总结。     

软磁性Co基块体非晶合金的研究进展

Co基非晶合金不仅具有高热稳定、高强度、硬度,还显示出优异的软磁特性如低矫顽力、高磁导率、低铁损、低磁致伸缩系数等,尤其是高频下的导磁率、铁损性能极佳,有着重要的工业应用价值.但相对于软磁性Fe基非晶合金,Co基的合金体系较少、玻璃形成能力(GFA)和饱磁感应强度较低而影响了它们的广泛应用.近年,材料工作者研发出了一系列Co基块体非晶合金体系,并对它们的非晶形成机理、GFA、过冷液态稳定性、结晶化行为、磁性及力学性能等进行了广泛、深入的研究.本文对软磁性Co基块体非晶合金的研究进展进行了简述,并展望了其今后的发展方向.     

溅射FeSiAl合金薄膜的结构及软磁性能

Ｓｅｎｄｕｓｔ合金是制做薄膜磁头和ＭＩＧ磁头的理想材料，本工作用射频溅射法了备了Ｓｅｎｄｕｓｔ成分的ＦｅＳｉＡｌｗ合金薄膜，研究了制备对膜结构和软磁性能的影响，并对其机理进行了讨论。     

入射角对微波在面内各向异性磁性薄膜中传播特征的影响

基于Maxwell方程组，探讨了面内各向异性磁性薄膜内磁导率的旋磁特性对微波在膜内传播性质的影响，揭示出不同角度入射的微波在膜内的传播性质具有显著差异。     

磁性薄膜微波噪声抑制器研究进展

噪声抑制器是现代通信电路中抗电磁干扰的一种重要手段.介绍了磁性薄膜噪声抑制器噪声抑制机理:铁磁谐振和焦耳热损耗.综述了薄膜的电阻率、三维尺寸以及其他方面因素对其噪声抑制性能的影响规律,指出存在一个最佳薄膜电阻使得噪声损耗达到最大,电磁辐射达到最小,且在一定范围内,随着薄膜长度和厚度的增加、宽度的减小,薄膜的谐振频率逐渐提高,噪声的功率损耗逐渐加大,噪声抑制性能明显提高.     

一种测量薄膜磁性的表面磁光克尔效应装置

介绍表面磁光克尔效应谱（ＳＭＯＫＥ）的一种新方案。通过适当分光并测量信号束和参考束的光强比，可以明显改善由于激光的光强不稳造成的误差，还使得随机偏振激光器也能用于ＳＭＯＫＥ装置。同时该方案中没有采用信号调制，因此对探测器等硬件要求很低。实验结果表明，采用光强稳定度为５％的普通国产Ｈｅ－Ｎｅ随机偏振激光器，其测量灵敏度能够达到目前国际上通常用于超薄膜磁性测量的ＳＭＯＫＥ的同类水平。     

一种测量薄膜磁性的表面磁光克尔效应装置

介绍表面磁光克尔效应谱（SMOKE）的一种新方案。通过适当分光并测量信号束和参考束的光强比，可以明显改善由于激光的光强不稳造成的误差，还使得随机偏振激光器也能用于SMOKE装置。同时该方案中没有采用信号调制，因此对探测器等硬件要求很低。实验结果表明，采用光强稳定度为5％的普通国产He－Ne随机偏振激光器，其测量灵敏度能够达到目前国际上通常用于超薄膜磁性测量的SMOKE的同类水平。     

电容位移法精确测量磁性薄膜的磁致伸缩系数

介绍了一种精确测量磁性薄膜磁致伸缩系数方法－电容位移法，并自行研制组装了一套测量装置，通过误差分析，仪器的精确标定，对稀土－铁超磁致伸缩薄膜的磁致伸缩系数进行了测量，获得满意的结果。     

Fe/Pt磁性薄膜的研究进展

Fe/Pt合金薄膜是重要的磁性材料.介绍了Fe/Pt合金的晶体结构以及磁控溅射法、真空电弧离子法、机械冷变形法和化学合成法4种主要制备Fe/Pt合金薄膜的方法,并对影响Fe/Pt合金薄膜磁性能的重要因素进行了评述,包括改变热处理工艺参数和添加掺杂元素.最后指出,Fe/Pt纳米结构材料具有良好的化学稳定性和较高的磁晶各向异性,因而在超高密度信息存储领域有着巨大的应用潜力.     

纳米磁性多层膜的微波电磁特性研究

采用射频磁控溅射法制备了FeCoB／SiO2纳米磁性多层膜,并对其微波特性进行研究。用微波谐振腔法测量了该薄膜的复磁导率．2GHz频率处复磁导率实部及虚部分别可达251和22．7。重点研究了多层膜结构中介质层厚度及薄膜总厚度对磁导率的影响,同时结合直流电阻率ρ、静态磁参数Bs、Hc的测量结果分析．探讨了纳米磁性多层膜的微波高磁导率机理．并提出了微波频率下获得高磁导率及低磁损耗的途径。实验结果也表明这种纳米磁性多层膜材料有望在高频平面变压器、平面电感器、薄膜电磁干扰抑制器等领域获得应用。     

纳米高频软磁薄膜材料研究进展

由于高频软磁薄膜材料具有巨大的应用前景因此获得了人们广泛的关注。对纳米合金软磁薄膜、纳米软磁颗粒膜、多层膜以及图形化薄膜进行了分类综述,分别介绍了各类薄膜的制备方法、化学成分、微观结构特点和高频物理性能,并对影响其性能的主要因素进行了讨论。由于纳米高频软磁薄膜材料相对于传统磁性材料具有显著优势,所以纳米合金软磁薄膜有望取代铁氧体作为制作高频磁性器件的主要应用材料。由于纳米软磁颗粒膜、多层膜以及新兴的图形化薄膜具有材料结构设计和物性剪裁的自由度,因此将是今后的重点研究方向。     

Study of the Usual and the Unusual Effect of a DC Magnetic Field on the Microwave Properties of Different Superconducting YBCO Thin Films

An experimental observation of the improvement of the microwave properties of high temperature superconductor thin film subjected to a weak DC magnetic field is reported. This characterization was done with two YBCO films deposited onto LaAlO₃ substrates and the coplanar resonator technique was used to extract their microwave properties. The results are presented as a comparison between the behaviors of a sample that exhibits an unusual effect with another sample that has a usual behavior. To understand the origins of such a difference, the crystallographic properties and the microstructure were investigated respectively by mean of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). A major difference in terms of growth axis orientation and of granularity has been observed between the two samples. Based on the correlated variation of the surface resistance and the surface reactance of the considered sample, the presence of anomalous weak links and also of a-axis grains in one of the films could explain its unusual behavior.     

钇改性PZT薄膜的极化印刻研究

铁电ＰＺＴ薄膜的极化印刻（ｉｍｐｒｉｎｔｉｎｇ）是ＰＺＴ不挥发存储器失效的重要原因之一．本文研究了不同钇量改性的ＰＺＴ（４０／６０）铁电薄膜在高温（１２０℃）和偏置电压下的极化印刻特性,发现适量的钇掺杂,改善了ＰＺＴ薄膜电容器单元的极化印刻．     

坡莫磁阻薄膜的热处理研究

研究了坡莫磁阻薄膜的热处理工艺对电磁性能和组织结构的影响。通过溅射样品退火处理前后的X射线和TEM分析表明退火后(111)织构加强,堆垛层错减少,晶粒长大,缺陷减少。退火后电阻率下降,各向异性磁阻提高,但软磁性能没有改善,这些是与微结构变化相联系的。     

退火处理Fe(Co)Al(Zr)O系薄膜磁性能的研究

采用射频磁控溅射装置在氩气氛下制备了Fe(Co)Al(Zr)O系薄膜.用X射线衍射仪、透射电镜及其选区衍射来分析薄膜的微结构.用振动样品磁强计、磁导计等测量了矫顽力Hc、饱和磁化强度Ms及磁导率等磁性参数.通过退火处理研究了Fe(Co)Al(Zr)O系薄膜的磁性能.Fe(Co)Al(Zr)O系薄膜磁各向异性是由形状各向异性引起的.     

Peculiarities of Pinning and Microwave Absorption Hysteresis in Thin Superconducting Films

The results of experimental and theoretical studies of the hysteretic microwave absorption (MWA) in the superconducting Bi₂Sr₂CaCu₂O₈ thin films are presented. It has been found experimentally that the hysteresis loop manifests some unusual features such as the non-monotone hysteresis variation and the change of a hysteresis sign. We have shown that such unusual behavior is due to the special nature of the bulk pinning in a superconducting film with a thickness comparable with the field penetration depth. The theoretical model of the MWA hysteresis has been developed taking into account the inhomogeneous distribution of centers with different symmetry of a pinning potential and their variation with the magnetic field value.     

钙钛矿型铁电薄膜疲劳性能研究进展

钙钛矿型铁电薄膜由于在非易失存储器方面的应用而受到广泛研究,但疲劳问题是影响其应用的主要障碍。简要综述了近年来国外在钙钛矿型铁电薄膜疲劳机制和消除疲劳措施等方面的研究进展。     

Linear-Defect-Induced Thermal Instability in YBCO Thin Films in Microwave Fields

An induced heat instability proposed to explain the difference between microwave properties of YBCO single crystals and thin films at temperatures just below T _c. Extended strain fields near out-of-plane edge dislocations are initial discontinuities for the instability development. We have shown theoretically and have confirmed experimentally that a single dislocation can not have a strong effect on the microwave surface resistance R _s. Dislocation arrays, which were observed experimentally, can induce the thermal instability if edge dislocations in the arrays are spaced closer than the heat relaxation length. Ordered dislocation structures provide much higher local temperature perturbation than randomly distributed dislocations.     

Correlation of Magnetic Properties of Co/Cr Bilayer Thin Films with Grain Boundary Diffusion

The microstructure and magnetic properties of Co/Cr bilayer films were examined before and after postdeposition annealing by using transmission electron microscopy (TEM), X-ray diffraction (XRD) technique and vibrating sample magnetometer (VSM). A model of grain boundary (GB) Cr-rich phase growth involving GB diffusion derived from the Cr underlayer was proposed to elucidate the kinetics of the paramagnetic Crrich phase growth along Co GBs within the Co layer. The correlation of the GB Cr-rich phase formati...