在透射电子显微镜中，实现纳米尺度上定量磁参数的测量一直是一个具有挑战性的难题。电子磁手性二向色性技术（EMCD）的发明，实现了利用透射电子实现材料磁性测量的新方法，也是继洛伦兹技术和电子全息技术之后，透射电镜中又一种新的磁性表征手段。但是EMCD技术仍然是一门发展中的技术，在使用过程中还存在一些问题需要解决，完善和拓宽EMCD技术，对于透射电镜中纳米尺度上的磁性表征具有重要的意义。本论文首先建立了一套EMCD技术定量磁参数测量的一般方法，以石榴石结构的Y3Fe5O12为例，实现了定量磁参数测量。主要包括以下三个方面：建立了一套寻找衍射动力学条件的一般方法，打破了占位分辨EMCD技术对晶体结构的限制；指出了三束衍射几何中的不对称性，为实验中信号采集位置的选择提供了指导；通过信号模拟，优化了实验中信号采集光阑的位置，提高了信噪比。并且，针对一些特殊的体系，提出了正带轴衍射几何，结合理论模拟，在实验上实现了正带轴下EMCD信号的探测。其次，发展了面内EMCD磁性测量技术，将EMCD技术测量从平行于电子束方向拓宽到垂直于电子束方向，实现了材料本征状态下磁性质的测量。并且利用Co纳米片，结合理论模拟和实验设计，在Lorentz模式下，首次实现了面内EMCD信号的探测。此外，将会聚束衍射与EMCD技术结合，实现了高空间分辨的磁性测量，同时结合透射电镜中其他先进的结构表征手段，实现了协同表征。研究了Y3Fe5O12-Pt界面的原子、电子结构，化学成分和磁性质，从微观结构上揭示界面自旋流下降的微观机制。 最后，利用Lorentz和电子全息技术研究了skyrmion纳米条带中边缘磁组态在外界温度场和磁场下的演化过程，揭示了边缘态的磁结构，解释了skyrmion在边缘形核和消失的微观机制。并且将透射电镜中三种磁性表征技术进行了对比分析，讨论了它们在结合使用表征磁性材料的过程中可能存在的问题以及解决的方案。
One of the most challenging issues when characterizing magnetic materials in the transmission electron microscope is to obtain quantitative magnetic parameters at the nanometer scale. Electron magnetic chiral dichroism is a new technique that allows the local magnetic properties of materials to be quantitatively measured with close-to-atomic spatial resolution and element specificity in the TEM, following the Lorentz microscopy and off-axis electron holography. However, there are still many problems to be addressed and much room to be developed before it becomes a more general and powerful technique for magnetic characterization in the TEM.In this dissertation，a general way to achieve the quantitative measurement of magnetic parameters are firstly developed. Y3Fe5O12 is used to demonstrate the general method and the magnetic parameters with element-specific and site-specific are obtained. Three main parts are involved: the way of seeking diffraction conditions required for quantitative measurement is established to break through the limitation of site-specific EMCD technique; the up-down asymmetry in the present three-beam case is pointed out to guide the experimental design for intrinsic EMCD signals; the simulations are conducted to optimize the detector positions to improve the signal-noise-ratio. Furthermore, the diffraction geometry is extended to the zone axis with higher symmetry. The EMCD signals for Y3Fe5O12 are experimentally detected with the assistant of theoretical simulations under the zone axis diffraction condition. The in-plane EMCD technique is developed under a new specific diffraction geometry, compared to the traditional out-of-plane EMCD technique, making it possible to measure the intrinsic magnetic properties. The experimental results recorded from a Co nanoplate under the Lorentz mode are consistent with the simulations, demonstrating that an EMCD signal originating from in-plane magnetization can be detected successfully. In addition, by combining the converged beam electron diffraction with EMCD technique, the magnetic measurement with high-spatial resolution is applied the Y3Fe5O12-Pt interface. Along with the analysis of atomic structure, electron structure and chemical composition by some other advanced techniques in the TEM, the origin of disorder layer at the interface is revealed and the decreased efficiency of spin current transport is attributed to the deteriorated magnetic properties. At last, the other two magnetic characterization techniques, Lorentz microscopy and off-axis electron holography, are demonstrated to study the evolution of magnetic edge-states in geometrically confined FeGe skyrmion nanostripe. The magnetic vectors of the edge-states are quantitatively measured to explain the underlying mechanism of nucleation and alinilation of skyrmion at the edge of nanostripe under the stimuli of spin polarization current. These three different techniques are together compared, and the possible obstacles and corresponding solutions are addressed during their combination for magnetic characterization.
