Development of a high-energy-, high-spatial-, and high-momentum-resolution electron energy loss spectrometer with liquid-Helium cooling stage (HR3-EEL spectrometer)

开发具有液氦冷却级的高能、高空间、高动量分辨率电子能量损失谱仪（HR3-EEL谱仪）

• 批准号: 461150024
• 负责人: Dr. Thomas Gemming
• 金额: --
• 依托单位: Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden (IFW) e.V.
• 依托单位国家: 德国
• 项目类别: New Instrumentation for Research
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/461150024?language=en
• 关键词: Development; energy; spatial; momentum; resolution

The last two decades have witnessed substantial development of spectroscopy techniques that probe low-energy excitations in solids, which, in many cases, lead to important breakthroughs in the understanding of fundamental solid-state effects. Prominent examples are Angular Resolved Photoemission Spectroscopy (ARPES) or Scanning Tunneling Spectroscopy (STS), which, amongst others, demonstrated the existence of gapless surface states in topological insulators and anisotropic gaps in high-temperature superconductors. That was possible because these techniques probe excitations at the surface with an excellent energy resolution (meV regime and below depending on cryogenic conditions) and high spatial or angular resolution. Nevertheless, a spectroscopic technique for analyzing electronic and vibrational excitations in the bulk (and surface) with simultaneous high-energy, high-momentum, and high-spatial resolution down to deep cryogenic conditions (liquid Helium cooling) is still missing. Such a tool would, for instance, allow studying the diverse class of low-dimensional structures (e.g., interfaces, van der Waals materials) with high momentum resolution in the extended dimensions, while maintaining high-spatial resolution in the inhomogeneous direction. It would allow deliberately tailoring spatial and momentum resolution for investigating the details of the dielectric response in complex nanostructures (e.g. nanophotonic and electronic devices, organic semiconductors, but also defects) including non-local dielectric response effects such as spatial variations in the dielectric dispersion. It is the aim of this project to realize this ambition by building a comprehensively improved Transmission Electron Energy Loss spectrometer. Crucial ingredients are a newly developed magnetic ground potential monochromator, a new continuous flow L-He sample stage, an improved sector magnet energy filter, and fast 2D CMOS electron detectors, which are integrated into an adapted state-of-the-art TEM platform including a cold field emission gun and a comprehensive, freely configurable condenser and projection optics, amongst others. The instrument will reach sub 10 meV energy resolution, few nm spatial resolution, sub 1/µm momentum resolution, and sub 10 K temperature in parallel in EEL spectroscopy mode as well as atomic resolution, electric and magnetic field sensing in other operation modes. This breakthrough in various key figures allows drastically widen our basic understanding of the charge density response function in various topical materials such as high-Tc superconductors, topological insulators, Weyl and Dirac semimetals, plasmonic nanostructures, organic semiconductors, soft biologic matter, or correlated matter, providing insight into their specific and universal ground state and dynamic properties (e.g., charge transport, dielectric response, electronic and phononic band structure, charge ordering).

在过去的二十年里，光谱技术有了长足的发展，探测固体中的低能激发，在许多情况下，这导致了对基本固态效应的理解的重大突破。 突出的例子是角分辨光电子能谱（ARPES）或扫描隧道能谱（STS），其中包括证明拓扑绝缘体中存在无隙表面态和高温超导体中存在各向异性间隙。这是可能的，因为这些技术探测激发在表面具有优异的能量分辨率（meV制度和以下，取决于低温条件）和高空间或角分辨率。然而，一种光谱技术，用于分析电子和振动激发在体（和表面）与同时高能量，高动量，高空间分辨率下降到深低温条件（液氦冷却）仍然是失踪。例如，这样的工具将允许研究不同类别的低维结构（例如，界面、货车德瓦尔斯材料），在扩展维度上具有高动量分辨率，同时在非均匀方向上保持高空间分辨率。 它将允许故意定制空间和动量分辨率，用于研究复杂纳米结构（例如纳米光子和电子器件，有机半导体，还有缺陷）中的介电响应的细节，包括非局部介电响应效应，例如介电色散的空间变化。本项目的目标是通过建立一台全面改进的透射电子能量损失谱仪来实现这一目标。关键成分是一个新开发的磁地电位单色器，一个新的连续流动L-He样品台，一个改进的扇形磁铁能量过滤器，和快速2D CMOS电子探测器，这是集成到一个适应国家的最先进的TEM平台，包括一个冷场发射枪和一个全面的，可自由配置的聚光镜和投影光学，等等。该仪器将在EEL光谱模式下并行达到低于10 meV的能量分辨率，几nm的空间分辨率，低于1/µm的动量分辨率和低于10 K的温度，以及在其他操作模式下的原子分辨率，电场和磁场传感。在各种关键数据中的这一突破允许极大地拓宽我们对各种主题材料中的电荷密度响应函数的基本理解，例如高Tc超导体，拓扑绝缘体，Weyl和Dirac半金属，等离子体纳米结构，有机半导体，软生物物质或相关物质，提供对其特定和通用基态和动态特性的洞察（例如，电荷传输、介电响应、电子和声子能带结构、电荷排序）。