Jozwiak C, Graf J, Lebedev G, Andresen N, Schmid A K, Fedorov A V, El Gabaly F, Wan W, Lanzara A, Hussain Z
Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Rev Sci Instrum. 2010 May;81(5):053904. doi: 10.1063/1.3427223.
We describe a spin-resolved electron spectrometer capable of uniquely efficient and high energy resolution measurements. Spin analysis is obtained through polarimetry based on low-energy exchange scattering from a ferromagnetic thin-film target. This approach can achieve a similar analyzing power (Sherman function) as state-of-the-art Mott scattering polarimeters, but with as much as 100 times improved efficiency due to increased reflectivity. Performance is further enhanced by integrating the polarimeter into a time-of-flight (TOF) based energy analysis scheme with a precise and flexible electrostatic lens system. The parallel acquisition of a range of electron kinetic energies afforded by the TOF approach results in an order of magnitude (or more) increase in efficiency compared to hemispherical analyzers. The lens system additionally features a 90 degrees bandpass filter, which by removing unwanted parts of the photoelectron distribution allows the TOF technique to be performed at low electron drift energy and high energy resolution within a wide range of experimental parameters. The spectrometer is ideally suited for high-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES), and initial results are shown. The TOF approach makes the spectrometer especially ideal for time-resolved spin-ARPES experiments.
我们描述了一种自旋分辨电子能谱仪，它能够进行独特高效且具有高能量分辨率的测量。通过基于铁磁薄膜靶的低能交换散射的极化测量来实现自旋分析。这种方法可以实现与最先进的莫特散射极化仪相似的分析能力（谢尔曼函数），但由于反射率提高，效率提高了多达100倍。通过将极化仪集成到基于飞行时间（TOF）的能量分析方案中，并配备精确且灵活的静电透镜系统，性能得到进一步提升。与半球形分析仪相比，TOF方法能够并行采集一系列电子动能，从而使效率提高一个数量级（或更多）。该透镜系统还具有一个90度带通滤波器，通过去除光电子分布中不需要的部分，使得TOF技术能够在低电子漂移能量和高能量分辨率下，在广泛的实验参数范围内进行。该能谱仪非常适合高分辨率自旋和角分辨光电子能谱（自旋-ARPES），并展示了初步结果。TOF方法使该能谱仪特别适用于时间分辨自旋-ARPES实验。
