静态磁光薄膜表面温度场的有限元法分析

建立了磁光薄膜在脉冲激光作用下的传热模型,利用有限元法对磁光薄膜表面的温度场进行了模拟计算,讨论了磁光薄膜在不同环境温度下的升温特性,这些结果可以用于对磁光薄膜宽温化、表面温度特性、磁光记录畴尺寸和表面形貌等的研究。     

小波分析方法在磁光记录薄膜基本特性分析中的应用

利用小波分析方法取代传统的傅立叶方法对微弱的磁光记录薄膜信号进行分解、滤波和局部信号处理,大大提高了测量的灵敏度,更好地分析了磁光记录薄膜的基本特性。     

溅射氩气压对TbFeCo薄膜磁和磁光性能的影响

研究了射频磁控溅射氩气压的变化对TbFeCo薄膜的磁和磁光特征的影响，以及不同溅射氩气压下TbFeCo薄膜退火后的特性，溅射氩气压的变化通过改变表面状态影响TbFeCo薄膜矫顽力和克尔角，另外，溅射氩气压的变化会影响被溅射原子轰击薄膜的速度，从而影响TbFeCo薄膜的垂直磁各向异性，矫顽力，磁光点尔效应。     

基于遗传算法的磁光记录薄膜的温度特性计算

介绍了计算磁光记录薄膜温度特性的基本原理,提出了RE-TM磁光记录薄膜温度特性计算的遗传算法.着重分析了算法实现中的关键步骤,包括适应函数的选取及定标、遗传算子的选取.实验证明该算法快速有效, 收剑性好.     

MATLAB在磁光记录薄膜温度特性研究中的应用

简要介绍了MATLAB软件及其主要特点,讨论了磁性材料的温度特性及其测量方法,重点分析了MATLAB在磁光记录薄膜温度特性研究中的应用：通过插值方法用已知实验数据点估算新的数据点,应用MATLAB数学函数求解磁光记录薄膜各功能层的居里温度。本文的具体实例表明,在磁学研究中使用MATLAB可以提高实验效率。     

SmTbFeCo磁光记录材料温度特性的平均场理论研究

基于平均场理论，提出重稀土－轻稀土－过渡族非晶薄膜温度特性的计算方法，详细讨论了薄膜成分对薄膜磁学和磁光性能的影响。研究表明，用适量的轻稀土元素替代重稀土元素，室温下饱和磁化强度增大，克尔角有所提高，薄膜的补偿点温度下降，恧大里点温度基本保持不变，并且饱和磁化强度和矫顽力随温变化趋向缓慢，从而可以拓宽磁光介质的使用温度范围。     

非晶SmDyFeCoTi薄膜的磁和磁光特性

用射频磁控溅射法制备了一系列的（ＳｍＤｙＦｅＣｏ）１－ｘＴｉｘ薄膜,研究了Ｔｉ对非晶ＳｍＤＦｅＣｏ磁光薄膜磁、磁光特怀及其热稳定性的影响,结果表明,少量的Ｔｉ原子掺杂对非晶ＳｍＤｙＦｅＣｏ薄膜的磁和磁光特性影响小,但提高了它的磁和磁光特性的热稳定性。     

基于磁光波导的YIG薄膜材料研究进展

首先介绍了磁性石榴石的晶体结构和元素替代理论,然后重点介绍了Bi:YIG与Ce:YIG薄膜的制备方法和磁光特性。降低吸收损耗和增大Ce、Bi离子含量可以增大石榴石薄膜的磁光优值。薄膜良好的磁光性能依赖于合理的制备工艺。Ce-,Bi-YIG是制备磁光波导器件的良好材料。     

磁光记录材料读写老化实验系统

利用热磁记录方法,通过聚焦到微米级的激光束可将亚微米级的磁畴写入磁光记录薄膜中去。而利用极向克尔效应则可读出磁畴信息。其特点是记录介质可擦,重复使用。本文提出一种磁光记录材料读写老化试验系统。在脉冲重复频率约50kHz 范围内为磁光薄膜提供擦写用的高达数万安每米的连读正负极性的脉冲磁场,脉宽τ。约2μs。讨论了在电感负载上获得窄脉冲大电流的方法。利用二阶 RLC 网络其输出电流可获得较佳的效果。     

磁光合金膜的磁控溅射

采用直流磁控溅射技术,配备自行设计的可调薄膜成份的BF—250型矩形平面区控电磁靶,制备了多种成份的Gd-Fe、Gd-Tb-Fe磁光合金薄膜。实验表明,BF-250型电磁靶调节薄膜成份,规律性好,调节范围宽,能够镀制出非晶态的垂直磁化磁光光盘介质薄膜,对于Gd-Tb-Fe磁光膜,(Gd+Tb)总含量为24at％左右,Gd与Tb的原子数比为1.5～1.7时,磁光特性较好。     

内置介质板的开孔箱体屏蔽效能电磁拓扑模型

针对内置介质板的开孔矩形金属箱体的特点,基于电磁拓扑(EMT)理论和BLT方程,建立任意平面波照射下箱体屏蔽效能的EMT模型,推导近似计算解析式,并分析介质板的厚度、材料和位置及平面波的极化角和入射角等因素对屏蔽效能的影响。结果表明:加装介质板可有效抑制箱体谐振,显著提高谐振点附近的屏蔽效能,但对远离谐振点频域的屏蔽效能影响不大;介质板厚度越大,屏蔽效能越高;不同谐振点处存在最佳电导率和最佳相对介电常数,使得谐振的抑制作用最强,屏蔽效能最高;介质板置于箱体前端比后端屏蔽效能高;不同谐振点处屏蔽效能的最大值在不同的介质板位置处取得;平面波的极化角越大,入射方位角越大,仰角越小,屏蔽效能越高。计算结果与仿真结果一致,证明了该文建立的EMT模型的有效性。该方法较等效传输线法(TLM)计算精度更高,尤其是在高频范围;较数值方法和全波仿真计算方法速度更快。该文工作对屏蔽箱体的设计具有指导意义。     

A detection method of differences of polarization angles between three‐component signals

I describe a new method of detecting differences of polarization angles, azimuth and elevation angle, between two three‐component signals. The differences of polarization angles are calculated directly from nine cross‐correlations between two three‐component signals. I compare the performance of this method to a conventional method based on a polarization filter, which uses Principal Component Analysis, in a computer simulation. When data length is shorter than a period of a sinusoidal signal, which is used as a signal in the simulation, the new method shows both less dispersion and less bias of errors than the polarization filter does. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(1): 45–53, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10044     

HEMP场激励下交直流高压输电线耦合响应概率分布

应用蒙特卡罗法和传输线耦合响应节点导纳方程,分析了高空核电磁脉冲(HEMP)场激励下交流高压输电线和直流高压输电线耦合响应的分布规律.分析中将电磁波的入射参数,包括极化角、入射角和方位角,作为一组随机变量,并由计算机随机产生.应用瞬态外场激励下多导体传输线节点导纳方程分别分析端接传输线耦合电流和耦合电压响应峰值,并得出...     

Thin film lithium niobate for use in silicon based devices

The incorporation of a thin film of lithium niobate (LiNbO3) in a conventional MOS (metal-oxide-semiconductor) structure gives the possibility of two fundamentally different types of computer memory architectures. One, based on ferroelectric switching involves the reorganization of charge in the transistor channel to compensate for the change in polarization. Another, based on the bulk photovoltaic effect, involves a shift in the transistor threshold with exposure to differing intensities of incident light. With the use of a molybdenum liftoff process, transistors have been fabricated in which LiNbO3 replaces the usual gate oxide of an MOS transistor. Transistor parameters such as the transconductance, output conductance, and amplification for these devices are reported.     

An interface charge model for ferroelectric field effect transistor

An interface charge model for ferroelectric-gate field-effect transistor (FeFET) is developed by combining the basic device equations of metal-oxide-semiconductor field-effect transistors with the polarization characteristics of ferroelectric thin films. This model presents the characteristics of FeFET considering interface charge between the ferroelectric thin film and the insulator layer. Simulations demonstrate that the interface charge will cause the surface potential of the semiconductor and the drain current left shift, and the memory windows are narrowed down, which are resulted from the space charge of the surface of the semiconductor. Meanwhile, the value of polarization almost does not change in FeFET. Furthermore, the simulation of FeCMOS indicates that the output voltage will left shift as the interface charge increases.     

PZT capacitor with Ir/IrO2/Ir electrode fabricated by RTA

Abstract

PZT capacitor with direct contact between Si substrate and bottom electrode of the capacitor was obtained with Ir/IrO₂/Ir/Ti electrode, by crystallizing sol-gel PZT thin film using RTA (650°CC 30 sec.). Contact resistance for hole diameter of 0.72 μm was 19 Ω. It was observed by cross-sectional TEM that Ti silicide was formed at the interface, but there was not oxygen diffusion from PZT thin film. Fatigue property of the PZT thin film was improved by RTA compared with furnace annealed film (600°CC 60 min.). The absolute value of the remnant polarization was 13 μC/cm² for both films, but it did not degrade until 10⁸ cycles of switching for the film by RTA, while it degraded before 10⁵ cycles for furnace annealed film.     

Effect of Domain Nucleation on Switching of Ferroelectric Thin Films

Domain nucleation close to a domain wall and within an unswitched domain of a ferroelectric thin film is analyzed theoretically in terms of the local field, from which a model of ferroelectric polarization switching is developed. The coercive field is calculated as a function of film thickness, and the prediction is found to be in good agreement with experiments on PbZr x Ti 1 m x O 3 thin films.     

Imprint Characteristics of Bi-Layered Perovskite Ferroelectric Thin Films

The imprint characteristics of SrBi₂Ta₂O₉, SBT, and (Bi_0.8La_0.2)₄Ti₃O₁₂, BLT, thin film capacitors have been evaluated at the storage temperature of 125 □. The coercive voltage shift and the polarization loss occurred as a function of the logarithmic storage time. BLT capacitors showed more stable imprint characteristics than SBT. The increasing rate of the coercive voltage shift and the decreasing rate of the polarization loss of BLT with a storage time were smaller than that of SBT. The BL sensing signals were measured on 2T2C-256 Kbits FeRAM adopted SBT and BLT capacitor in order to estimate the imprint life times of the devices, respectively.     

Preparation and properties of Pb(Zr, Ti)O3 ferroelectric thin films and compositionally graded thin films on LaNiO3/Si substrates

LaNiO₃ (LNO) thin films were prepared on Si (100) wafer by MOD method. Pb(Zr, Ti)O₃ ferroelectric thin films and their compositionally graded thin films were prepared on LNO/Si (100) substrates by a modified sol–gel method. The composition depth profile of a graded film was determined by using a combination of Auger electron spectroscopy and Ar ion etching. The results confirmed that the processing method produces graded composition change. XRD analysis showed that the graded thin film possessed a composite structure of tetragonal and rhombohedral. The dielectric constant of the graded thin films was higher than that of each thin film unit, but the loss tangent was near to each other at 10 kHz. The temperature characteristics of the dielectric constant of the graded thin films at different frequencies showed three peaks and ferroelectric relaxor feature to some extent. Hysteresis loops showed that graded thin film had higher remanent polarization, smaller coercive field than each thin film unit. The pyroelectric coefficient of the graded thin films increased gradually with temperature, and was higher than that of each thin film unit.     

A magneto-optic current transducer

A current measurement technique using the magneto-optic or Faraday effect, has been developed, tested, and demonstrated. The device developed is a magneto-optic current transducer (MOCT). It uses the rotation of the plane of polarization by a magnetic field exhibited in certain glasses (Faraday effect). Test data obtained in an extensive field evaluation of the MOCT were compared with the design qualification data gathered during the development phase of this project. The analysis indicates that operation of the MOCT-based metering system under field conditions compares favorably with performance predicted during design qualification