Electron hydrodynamics arises when momentum-relaxing scattering processes are slow compared to momentum-conserving ones. While the microscopic details necessary to satisfy this condition are material-specific, experimentally accessible current densities share remarkable similarities. We study the dependence of electron hydrodynamic flows on the rates of momentum-relaxing and momentum-conserving scattering processes in a microscopics-agnostic way. We develop a framework for generating random collision operators which respect crystal symmetries and conservation laws and which have a tunable ratio between the momentum-conserving and momentum-relaxing lifetimes. Using various random instances of these collision operators, we calculate macroscopic electron viscosity tensors and solve the Boltzmann transport equation (BTE) in a channel geometry over a grid of momentum-conserving and momentum-relaxing lifetimes, and for different crystal symmetry groups. We find that different random collision operators using the same lifetimes produce very similar current density profiles, meaning that the current density is primarily a probe of the overall rates of momentum conservation and relaxation. By contrast, the viscosity tensor varies substantially at fixed lifetimes, meaning that properties like channel resistance provide detailed probes of the underlying scattering processes. This suggests that, while details of the scattering process are imprinted in the electronic viscosity tensor, for many applications theoretical calculations of hydrodynamic electron flows can use experimentally-available lifetimes within a spatially-resolved BTE framework rather than requiring the costly computation of ab initio collision operators.
Probing exciton interaction with a spatially defined charge accumulation layer in the organic semiconductor Diindenoperylene
利用有机薄膜晶体管（OTFT）的光致发光（PL）和载流子输运测量，研究了激子和载流子之间的微观相互作用。为此目的，原型有机半导体二茚并萘嵌苯（DIP）被用作活性物质。OTFT累积层提供了空间限定的电荷和光生激子的相互作用区，导致PL强度降低高达4.5%。这种效应与累积的空穴载流子密度相关，并为非辐射激子-空穴过程的横截面提供了约1.3E-10 cm 3/s的较低估计。这是合理的，这些过程优先介导的陷阱空穴。
Probing Anharmonic and Heterogeneous Carrier Dynamics Across Sublattice Melting in a Minimal Model Superionic Conductor
The University of Osaka（大阪大学）；Nagoya University（名古屋大学）；National Institute of Advanced Industrial Science and Technology（产业技术综合研究所）；RIKEN（理化学研究所）；Institute of Integrated Research, Institute of Science Tokyo（东京科学大学综合研究机构）
Operando Raman probing of mode selective electron phonon coupling in two dimensional halide perovskites
Institut national de la recherche scientifique（国家科学研究学院）；Eindhoven University of Technology（埃因霍温理工大学）；CNR NANOTEC, c/o Department of Chemistry, University of Bari（巴里大学化学系附属意大利国家研究委员会纳米技术研究所）；Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente（特温特大学科学与技术学院及MESA+纳米技术研究所）
Probing Topological Surface States and Conduction via Extended Defects in (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ Films
University of Michigan（密歇根大学）；University of Illinois（伊利诺伊大学）；Kirklareli University（克尔克拉雷利大学）；Penn State University（宾夕法尼亚州立大学）；Istanbul Technical University（伊斯坦布尔理工大学）
Probing the anisotropic behaviors of black phosphorus by transmission electron microscope, angular-dependent Raman spectra and electronic transports measurements
Direct probing of phonon mode specific electron-phonon scatterings in two-dimensional semiconductor transition metal dichalcogenides: Symmetry and Berry phase
Probing spatial extent of topological surface states by weak antilocalization experiments
弱反局域化测量已经成为研究拓扑材料中量子相干输运的标准工具。它通常用于提取有关导电通道数和拓扑表面态的退相长度的信息。我们研究了典型拓扑晶体绝缘体SnTe的薄膜。为了获得这些状态的微观特征，我们采用Tkachov和Hankiewicz开发的模型[Physical Review B 84，035444]。利用该模型，通过测量垂直和平行磁场组态中电导率的量子修正，得到了拓扑态的空间衰减。在这个模型中，我们发现两个拓扑边界之间的相互作用，导致在缩放的空间衰减与膜厚度。我们把这种行为归因于散装水库介导的相互作用，散射事件没有相打破的拓扑载流子。
Probing charge scattering mechanisms in suspended graphene by varying its dielectric environment
具有高载流子迁移率μ的石墨烯对于石墨烯基电子器件和石墨烯的狄拉克费米子的基本性质的研究都是必需的。人们普遍认为，石墨烯中的迁移率限制因素是驻留在石墨烯上或底层衬底中的带电杂质的库仑散射。这对于SiO2衬底上的传统石墨烯器件和最近报道的高迁移率悬浮和支撑器件都是如此。减少这种散射的有吸引力的方法是将石墨烯放置在具有高静态介电常数κ的环境中，这将有效地屏蔽由于杂质引起的电场。然而，到目前为止，实验仅报告了高κ环境对迁移率的适度影响。在这里，我们通过研究悬浮在液体中的多终端石墨烯器件中的电输运来研究石墨烯的介电环境的影响，其中κ范围从1.9到33。对于非极性液体（κ<5），我们观察到μ随着κ快速增加，并报告了石墨烯器件在苯甲醚（κ=4.3）中的室温迁移率高达约60，000 cm 2/Vs，而在极性液体（κ>18）中，我们观察到迁移率急剧下降。我们证明，非极性液体通过筛选吸附在石墨烯上的带电杂质来增强流动性，而极性液体中的带电离子引起所观察到的流动性抑制。此外，使用分子动力学模拟，我们建立了平面外弯曲声子的散射，在室温下在真空中悬浮石墨烯中的主要散射机制，被液体的存在抑制。我们希望我们的研究结果可以提供控制和减少未来石墨烯电子器件中载流子散射的途径。
