A consistent theory of electron energy-loss spectroscopy (EELS) includes two indispensable elements: (i) electronic response of the target system and (ii) quantum kinematics of probing electrons. While for the bulk materials and their surfaces separating these two aspects and focusing on the former is the usual satisfactory practice (the energy-loss functions formalism), we show that, for quasi-2D crystals, the interplay of the system's electronic response and the details of the probe's motion affects EEL spectra dramatically, and it must be taken into account for the reliable interpretation of the experiment. To this end, we come up with a unified theory which, on the same footing, treats both the long- and short-range scattering, within both the transmission and reflection experimental setups. Our calculations performed for graphene reveal a phenomenon of a strong coupling between the $π+σ$ plasmon excitation and elastic {\it scattering resonances}. Freed from the conventions of the energy-loss functions formalism, our theory serves as a consistent and systematic means of the understanding of the EELS of quasi-2D materials.
Electronic Transport in Electron-Phonon Gas of Two-Dimensional Holstein's Organic Molecular-Crystal: Non-equilibrium Green's Function Formalism & Boltzmann Transport Framework (A Generalized Mathematical Solution)
Femtosecond Laser-induced Crystallization of Amorphous Sb2Te3 film and Coherent Phonon Spectroscopy Characterization and Optical Injection of Electron Spins
采用飞秒激光辐照晶化技术将非晶Sb_2Te_3薄膜转变为晶化薄膜。利用高灵敏度的相干声子谱（CPS）技术研究了非晶Sb_2Te_3薄膜在辐照后的晶化过程。CPS揭示了对应于晶体Sb 2 Te 3的特征声子模式的两个声子模式的振动强度，随着激光照射能量密度（LIF）的增加而增强，显示出LIF的结晶度的上升，并且飞秒激光照射是一种良好的后处理技术。利用时间分辨圆偏振泵浦-探测光谱研究了激光诱导晶化Sb_2Te_3薄膜的电子自旋弛豫动力学。实验结果证实了自旋相关的光学跃迁选择定则的有效性和基于自旋光栅的类Sb 2 Te 3拓扑绝缘体自旋等离激元集体模瞬态光学探测方案的可行性.
Landau level spectroscopy of PbSnSe topological crystalline insulator
本文报道了一种拓扑晶体绝缘体Pb $_{1-x}$ Sn $_x$ Se的红外磁谱研究。我们已经检查了一组样品，所有的电子带的反转制度，与锡的成分从$x=0.2$到$0.33$变化。我们的分析表明，所观察到的响应，由一系列的带间朗道能级激发，可以解释和建模使用相对论性的三维大质量狄拉克电子的哈密顿量，扩展到包括对角二次项，施加带反转。在我们的数据中，我们没有发现任何明确的签名的无质量的电子状态，是目前的表面上的铅$_{1-x}$锡$_x$硒晶体在倒置制度。这种意想不到的结果的原因进行了讨论。
Spectroscopy of Wigner crystal polarons in an atomically thin semiconductor
University of Basel（巴塞尔大学）；Technical University of Munich（慕尼黑工业大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；National Institute for Materials Science（物质材料研究机构）
Probing the Polarization of Low-Energy Excitations in 2D Materials from Atomic Crystals to Nanophotonic Arrays using Momentum-Resolved Electron Energy Loss Spectroscopy
