Song Dongsheng, Dunin-Borkowski Rafal E
Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany.
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
Phys Rev Lett. 2021 Aug 20;127(8):087202. doi: 10.1103/PhysRevLett.127.087202.
Here we have developed an approach of three-dimensional (3D) measurement of magnetic moment vectors in three Cartesian directions using electron magnetic chiral dichroism (EMCD) at atomic scale. Utilizing a subangstrom convergent electron beam in the scanning transmission electron microscopy (STEM), beam-position-dependent chiral electron energy-loss spectra (EELS), carrying the EMCD signals referring to magnetization in three Cartesian directions, can be obtained during the scanning across the atomic planes. The atomic resolution EMCD signals from all of three directions can be separately obtained simply by moving the EELS detector. Moreover, the EMCD signals can be remarkably enhanced using a defocused electron beam, relieving the issues of low signal intensity and signal-to-noise-ratio especially at atomic resolution. Our proposed method is compatible with the setup of the widely used atomic resolution STEM-EELS technique and provides a straightforward way to achieve 3D magnetic measurement at atomic scale on newly developing magnetic-field-free TEM.
在此，我们开发了一种在原子尺度上利用电子磁手性二色性（EMCD）测量三个笛卡尔方向磁矩矢量的三维（3D）方法。在扫描透射电子显微镜（STEM）中使用亚埃收敛电子束，在扫描穿过原子平面的过程中，可以获得与束位置相关的手性电子能量损失谱（EELS），其携带了与三个笛卡尔方向磁化相关的EMCD信号。仅通过移动EELS探测器，就可以分别从所有三个方向获得原子分辨率的EMCD信号。此外，使用散焦电子束可以显著增强EMCD信号，尤其在原子分辨率下缓解了低信号强度和信噪比的问题。我们提出的方法与广泛使用的原子分辨率STEM-EELS技术的设置兼容，并为在新开发的无磁场透射电子显微镜上实现原子尺度的三维磁测量提供了一种直接的方法。
