具占位分辨的透射电子定量磁结构测量方法研究

磁性是物质的基本属性之一。中子衍射、X射线磁圆二色谱、电镜中全息术和Lorentz电镜是常用的研究磁性方法，但它们都难以做到纳米尺度的定量磁结构表征。2006年Schattschneider等基于透射电镜/电子能量损失谱技术提出了电子能量损失磁手性二向色谱（EMCD）测量磁结构方法，它具有元素分辨、高空间分辨等特点。2012年朱静等提出了占位EMCD技术，利用电子衍射动力学面通道效应和EMCD结合，实现了对具有特定点阵结构物质的磁性测量，获得了具有原子占位分辨的定量磁结构信息。本申请项目将聚焦于发展新的定量磁结构测量方法，即在对试样的晶体点阵结构没有限制的条件下，调控电子衍射动力学条件，增强和调制磁手性二向色谱信号，能获得具有高空间分辨、原子占位分辨、元素分辨、轨道与自旋磁矩分辨的定量磁结构信息；并将其应用于铁基超导材料中纳米尺度相的磁结构测定。发展此新方法，将有利于纳米磁结构研究。

Magnetic property is one of the principle attributes of matter. Neutron diffraction, X-ray magnetic circular dichroism, electron holography in the TEM and Lorentz electron microscopy are the higher impact methods for magnetic research, however, by which it is difficult to characterize quantitative magnetic structure in nanometer scale. Based on the Transmission electron microscopy/Electron Energy-Loss Spectroscopy Schattschneider et al had developed electron energy-loss magnetic chiral dichroism (EMCD) method in 2006, which is of high spatial resolution and elements resolved characterization. Combining electron diffraction dynamical planar channeling effect and EMCD Zhu et al had proposed site-specific EMCD method in 2012, by which at the first time the quantitative magnetic structure information from a nano-meter region of a NiFe2O4 sample with specifically crystallographic lattice structure, that meets the plan channeling condition, were achieved. In this project we will focus on developing a novel method to determine the site-specific quantitative magnetic structure from samples with general crystallographic lattice structure by constructively selecting the specific dynamical transmitted electron diffraction conditions in electron energy-loss magnetic chiral dichroism experiments; and the magnetic property of the phases with nanometer scale in Fe-based superconductor will be measured by using the new method. It is believed this new method will be very much useful to investigate the magnetic structure in the phase separation in highly correlated electron systems and ferromagnetic/antiferromagnetic interfaces in magnetic multilayers, etc.