Measuring the orbital angular momentum spectrum of an electron beam.
Measuring the orbital angular momentum spectrum of an electron beam.
复制标题
DOI：
10.1038/ncomms15536
复制
发表时间：
2017-05-24
影响因子：
16.6
通讯作者：
Karimi E
中科院分区：
文献类型：
--
作者：
Grillo V;Tavabi AH;Venturi F;Larocque H;Balboni R;Gazzadi GC;Frabboni S;Lu PH;Mafakheri E;Bouchard F;Dunin-Borkowski RE;Boyd RW;Lavery MPJ;Padgett MJ;Karimi E
携带轨道角动量（OAM）的电子波的特征在于平行于其传播方向的量子化和无界磁偶极矩。当与磁性材料相互作用时，这些电子的波函数会发生固有的变化。因此，这种变化促使需要分析电子波函数，特别是它们的波前，以获得有关材料结构的信息。在这里，我们提出，设计和演示的纳米级全息图的基础上测量电子的OAM组件的空间分离它们的设备的性能。我们对OAM值在-10到10之间的电子的纯OAM态和叠加OAM态进行分类。我们采用该设备来分析受微米级磁偶极子影响的电子的OAM光谱，从而确定我们的分选机可以成为纳米级磁光谱学的仪器。表征携带轨道角动量的电子束的现有方法是低效的，因为它们允许一次测量一个OAM状态。在这里，作者展示了一种能够分析多种OAM状态的OAM光谱仪，以及探测磁性材料的潜在工具。
Electron waves that carry orbital angular momentum (OAM) are characterized by a quantized and unbounded magnetic dipole moment parallel to their propagation direction. When interacting with magnetic materials, the wavefunctions of such electrons are inherently modified. Such variations therefore motivate the need to analyse electron wavefunctions, especially their wavefronts, to obtain information regarding the material's structure. Here, we propose, design and demonstrate the performance of a device based on nanoscale holograms for measuring an electron's OAM components by spatially separating them. We sort pure and superposed OAM states of electrons with OAM values of between −10 and 10. We employ the device to analyse the OAM spectrum of electrons that have been affected by a micron-scale magnetic dipole, thus establishing that our sorter can be an instrument for nanoscale magnetic spectroscopy. Existing methods of characterizing electron beams carrying orbital angular momentum are inefficient as they allow measuring one OAM state at a time. Here the authors demonstrate an OAM spectrometer capable of analysing multiple OAM states and a potential tool for probing magnetic materials.