Frömter Robert, Hankemeier Sebastian, Oepen Hans Peter, Kirschner Jürgen
Institut für Angewandte Physik, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany.
Rev Sci Instrum. 2011 Mar;82(3):033704. doi: 10.1063/1.3534832.
A newly designed scanning electron microscope with polarization analysis (SEMPA or spin-SEM) for the acquisition of magnetic images is presented. Core component is the spin detector, based on the scattering of low-energy electrons at a W(100) surface in ultrahigh vacuum. The instrument has been optimized with respect to ease of handling and efficiency. The operation and performance of a general low-energy electron diffraction (LEED) detector for SEMPA have been modeled in order to find the optimum operating parameters and to predict the obtainable image asymmetry. Based on the energy dependence of the secondary electron polarization and intensity, the detector output is simulated. For our instrument with optimized performance we demonstrate experimentally 8.6% polarization asymmetry in the domain structure of an iron whisker. This corresponds to 17.2% image contrast, in excellent agreement with the predicted simulated value. A contrast to noise ratio of 27 is achieved at 5 ms acquisition time per pixel.
本文介绍了一种新设计的带有偏振分析功能的扫描电子显微镜（SEMPA或自旋扫描电子显微镜），用于获取磁图像。核心部件是自旋探测器，它基于低能电子在超高真空环境下于W(100)表面的散射。该仪器在操作简便性和效率方面进行了优化。为了找到最佳操作参数并预测可获得的图像不对称性，对用于SEMPA的通用低能电子衍射（LEED）探测器的操作和性能进行了建模。基于二次电子偏振和强度的能量依赖性，对探测器输出进行了模拟。对于我们性能优化的仪器，我们通过实验证明在铁胡须的畴结构中偏振不对称性为8.6%。这对应于17.2%的图像对比度，与预测的模拟值非常吻合。在每个像素5毫秒的采集时间下，实现了27的对比度噪声比。
