Investigation of structure and ultra-fast dynamic processes of topological materials with inversion symmetry breaking using transmission momentum microscopy

使用透射动量显微镜研究反演对称性破缺拓扑材料的结构和超快动态过程

• 批准号: 516525057
• 负责人: Dr. Olena Fedchenko, Ph.D.
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/516525057?language=en
• 关键词: Investigation; structure; ultra; fast; dynamic

Time-resolved transmission time-of-flight momentum microscopy (TR-TToFMM) combines two innovative research approaches: investigation of dynamic processes by ultrafast electron diffraction and high-resolution time-of-flight momentum microscopy using parallel recording. The aim of this project is studying of ultra-fast dynamic processes with a novel contrast mechanism, namely transmission electron diffraction combined with energy loss spectroscopy. Full field imaging of inelastic electron scattering (IES) offers knowledge on dynamic electronic degrees of freedom in topological materials, which is not accessible by any other experimental approach. Friedel’s rule excludes detection of inversion asymmetry in a crystal structure via kinematic (single-scattering) diffraction in the absence of additional absorption processes of scattered radiation. Emitter-specific electron diffraction allows the investigation of low-dimensional structures due to both: strong multiple scattering of electrons (larger elastic interaction cross-section) and local element specificity of the pronounced inelastic absorption processes. TR-TToFMM gives access to hitherto unexplored inelastic scattering processes such as dynamic Auger transitions and spin-dependent losses. The novel approach will be exemplified by studying a thermally-induced inversion symmetry breaking in doped 1T- and 2H-(Mo1-xWx)Te2.

时间分辨透射飞行时间动量显微镜（TR-TToFMM）结合了两种创新的研究方法：利用超快电子衍射研究动态过程和利用平行记录的高分辨率飞行时间动量显微镜。本项目的目的是利用一种新的对比机制，即透射电子衍射结合能量损失谱，研究超快动态过程。非弹性电子散射（IES）的全场成像提供了拓扑材料中动态电子自由度的知识，这是任何其他实验方法都无法获得的。在没有散射辐射的附加吸收过程的情况下，Friedel规则排除了通过运动学（单散射）衍射检测晶体结构中的反演不对称。由于电子的强多重散射（较大的弹性相互作用截面）和明显的非弹性吸收过程的局部元素特异性，发射体特异性电子衍射允许研究低维结构。TR-TToFMM提供了迄今为止尚未探索的非弹性散射过程，如动态俄歇跃迁和自旋相关损失。这种新方法将通过研究掺杂1T-和2H-(Mo1-xWx)Te2的热诱导反演对称性破缺来举例说明。