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双层异质晶体结构的电子磁手性二向色性谱解析

符潇潇*，胡绮雯，吴 楷，刘 广，李建军，黄晓旭*
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2023年 第42卷 第6期: 1000-6281（2023）06-689-008     下载地址：

双层异质晶体结构的电子磁手性二向色性谱解析

符潇潇*，胡绮雯，吴 楷，刘 广，李建军，黄晓旭*

（1.重庆大学材料科学与工程学院国际轻合金联合实验室（MOE），重庆  400044；

2.重庆大学沈阳材料科学国家研究中心，重庆 400044）

摘  要  电子磁手性二向色性（EMCD）是一种元素分辨的高分辨磁矩测量技术。目前针对单晶EMCD信号的解析已经发展出一套常规的方法，但对电子束先后与不同晶体作用时的EMCD信号还缺乏理解，本文针对后者进行深入探讨。基于上下晶体重叠的模型，讨论了下层晶体中弹性和非弹性散射对EMCD信号可能产生的影响。在弹性散射方面，当下层晶体中的二次衍射未打破上层晶体在特定取向下的衍射花样的对称性，使用加和定则可从EMCD信号中有效解析轨道自旋磁矩比。位错线平行于电子束的界面错配位错可能不会为定量结果带来显著误差。在多重散射方面，下层晶体的存在会降低电离边的跃变比，增强多重散射峰，增大轨道自旋磁矩比的定量结果，而且通过常规解卷积难以完全消除这种效应。

关键词 EMCD；二次衍射；多重散射；解卷积

中图分类号：TG115.27；O48；O76+.1  文献标识码：A  doi:10.3969/j.issn.1000-6281.2023.06.001

 

Electron magnetic chiral dichroism in superimposed crystals

FU Xiao-xiao1，2*, HU Qi-wen1, WU Kai1, LIU Guang1, LI Jian-jun1, HUANG Xiao-xu1，2*

(1. International Joint Laboratory for Light Alloys (MOE), College of Materials Science and Engineering, Chongqing University, Chongqing 400044,；2. Shenyang National Laboratory for Materials Sciences, Chongqing University, Chongqing 400044, China) 

Abstract  The electron energy-loss magnetic chiral dichroism (EMCD) technique is generally used to study materials with single crystal structures, while the EMDC signal in superimposed crystals along the beam path has not been well understood. Our work explores the EMCD in superimposed crystals. Using a model of two crystals overlapped along the electron beam path, we discussed the influence of additional elastic and inelastic scattering in the bottom crystal on the EMCD signal. For elastic scattering, the quantification of orbital to spin moment ratio from EMCD signal is effective when the diffraction in the bottom crystal does not break the symmetry of the diffraction pattern of the upper crystal at a specific orientation. The interfacial mismatch dislocations with dislocation line parallel to electron beam would not break the symmetry. For plural inelastic scattering, the existence of the bottom crystal possibly decreases the jump ratio of ionization edges, increases the probability of mixed scattering occurring in the whole system, introduces additional energy shift, and thus affects quantification results. The added EMCD signal intensity at different edges due to plural scattering affects the quantified orbital to spin moment ratio differently. A complete removal of plural scattering effect cannot be achieved by deconvolution.

Keywords  EMCD；double diffraction；plural scattering；deconvolution

 

 

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