【作者】 宋平；

【导师】 连洁；

【作者基本信息】 山东大学 ， 光学工程， 2011， 硕士

【摘要】 目前,磁光材料和器件成为现代通信、航天、雷达、医疗必不可少的关键材料。磁光椭偏技术是近几年发展起来的探测磁光材料磁学和光学性质的新技术,它能够通过探测克尔效应引起的反射光偏振状态的改变,给出体材料和纳米磁性膜的磁光特性,对研究磁性材料的磁各向异性、磁耦合等具有重要的意义。以磁光椭偏技术为基础的磁光椭偏仪可以与薄膜生长设备如磁控溅射设备、MBE结合在薄膜生长过程中进行原位测量,为薄膜生长的不同阶段提供精确参考,是指导薄膜生长的必备检测工具。磁光椭偏仪还可为原有磁光薄膜材料进行优化升级提供可靠的理论与实验基础,为寻找新型的磁光材料提供先进的测量工具。本论文较为系统的叙述了国内外磁光椭偏技术领域相关的研究成果,对目前应用广泛的椭偏测量和表面磁光克尔效应测量进行了分析,从理论和实验两方面对磁光椭偏技术进行了分析,成功的建设了磁光椭偏实验平台,并利用该平台测量了坡莫合金和纳米磁性膜的磁光性质,实验结果证明该平台可以达到纳米级的测量精度。此外,论文还从理论上分析了体材料及多层薄膜结构的磁光克尔效应,得到了纵向克尔偏转角的计算公式。论文的创新点如下：(1)将斩波器、锁相放大器引入磁光椭偏实验平台,利用半导体激光器代替原先的偏振激光器,降低了对激光器的精度要求,利用斩波器中调制盘,将连续激光变成脉冲激光；斩波器的方波作为锁相放大器的参考信号,探测器接收到的脉冲信号作为待测信号输入锁相放大器中进行数据计算、存储。论文对该实验平台的可靠性与精确性进行了一系列的实验,得到了良好的效果。(2)分析了保护层的复折射率对磁性材料的克尔偏转角的影响。在保护层厚度一定的情况下,克尔偏转角将随保护层折射率n的增大而增大,随消光系数k的增加而减小,比较了Al、Au、Cu、Ag、Ta作为保护层材料时,生长在GaAs衬底上的纳米Fe膜的纵向克尔偏转角的变化,为选择合适的保护层材料提供了理论和实验基础。更多还原

【Abstract】 Now the magneto-optical materials and devices are essential to modern communications, aerospace, radar, medical. Based on ellipometry technique and magneto-optical effect, Magneto-optical ellipometry can measured the optical constants and magnetic constants of magnetic materials. It has been widely applied in characterizing the magnetic properties of ultra-thin film and multilayer. Magneto-optical ellipometry, the necessary detection tools to guide the growth of thin film, can provide accurate information for the different stages of film growth and carry out in situ measurements; it can provide a reliable theoretical and experimental basis for the optimization and upgrading of the magneto-optical films; it can provide advanced measurement tools to find new magneto-optical storage materials.This thesis gives a systematic review of the developments of magneto-optical ellipsometry, also analyze the application of ellipsomentry and the measurement of surface magneto-optical Kerr effect. Moreover, the magneto-optical ellipsometry is successfully built by the analysis of theory and experiment of the magneto-optical ellipsometry. The magneto-optical properties of the permalloy and ultra-thin Fe film are obtained by using the magneto-optical ellipsometry. The result shows that the magneto-optical ellipsometry is suitable for study of the magneto-optical properties of a single atomic layer. The magneto-optical Kerr effect of the bulk and multilayer structure are theoretical analyzed, and a larger Kerr rotation angle is obtained through the experiments and computer simulation of the overlayer material. The main initiative contributions in this thesis include following aspects:(1) The magneto-optical ellipsometry reduces the demand of the accuracy of the laser by introduce the chopper and lock-in amplifier to this platform. And the cost of measurement is significant saved using the semiconductor laser instead of original polarized laser. The detector will receive a pulsed laser instead of continuous laser by setting the frequency of the choppers modulation. And the chopper can emit the square wave with the same frequency as the reference signal of the lock-in amplifier. A series of computer simulations and experiments have shown of the reliability and accuracy of Magneto-optical ellipometry.(2) The relationship between the complex refractive index of the overlayer and the magneto-optical Kerr rotation angle is proposed. The magneto-optical Kerr rotation angle will increase with the addition of the refractive index n of the overlayer, and with the decrease of the extinction coefficient k at the same thickness of the overlayer. And then a simulation was made with the samples which have different overlayers of Al、Au、Cu、Ag、Ta to find the best overlayer material.更多还原