TWIST-NANOSPEC: Development of Advanced Optical Nano-spectroscopy Techniques for Twistronics

TWIST-NANOSPEC：开发用于 Twistronics 的先进光学纳米光谱技术

• 批准号: EP/X02153X/1
• 负责人: Alexander Tartakovskii
• 金额: $ 26万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX02153X%2F1
• 关键词: TWIST; NANOSPEC; Development; Advanced; Optical

Twistronics exploits a new tunable atomic lattice periodicity called moiré superlattices (mSL) in few-atom-thick van der Waals heterostructures, which is shown and predicted not only to be important in fundamental physics towards highly tunable quantum phases in the condensed matter but also promising for future optoelectronic and quantum technology applications. Despite the great interest and high potential of twistronics, limited characterisation tools exist that can be directly applied for detailed investigation of mSLs on the nanoscale thus far impeding progress in this vibrant emerging field. Here, we aim to develop new nano-imaging techniques to directly observe mSLs in twisted transition metal dichalcogenides bilayers (built from two monolayers rotated with respect to each other) by utilizing several optical methods, including the linear and nonlinear optical spectroscopy realised using scattering-type scanning near-field optical microscope equipped with lasers enabling spectroscopy in a wide range of wavelengths in the visible, near-infrared and mid-infrared. Moiré excitons, a fundamental excitation in semiconducting mSLs will be probed in the linear regime as well as in the resonant second- and third-harmonic generation experiments sensitive to the symmetry of the excitonic states and the heterobilayer atomic lattice. Furthermore, our techniques will enable to "see below the surface" in samples with encapsulated dielectric or conducting layers, a feature unaccessible for surface scanning techniques. With our developed techniques, the mSL is expected to be visualised with advantages of high contrast, non-contact, and high resolution at room temperature. Our newly developed approaches for nano-imaging and nano-spectroscopy will provide fundamentally new insights in the behaviour of a unique but potentially very extended class of twisted heterostructures and will also be applicable in other nano-materials systems (such as perovskites), where nano-imaging and spectroscopy on the nanoscale are also highly desirable.

Twistronics利用了一个新的可调原子晶格周期性，称为Moiré超级晶格（MSL），其中几个零食范德华瓦尔瓦尔斯异质结构，该结构在浓缩问题中的基本物理学中显示和预测，它不仅在基本的物理学中很重要，还可以对未来的光elelectronic和量子技术应用进行高度可调的量子阶段。尽管互惠率具有极大的兴趣和高潜力，但仍有有限的表征工具可以直接应用，以详细研究迄今为止，在这个充满活力的新兴领域中，纳米级对纳米级的进展却阻碍了进步。在这里，我们旨在开发新的纳米成像技术，以直接观察扭曲的过渡金属二甲化物双层中的MSL双层（由两个彼此旋转的单层构建），通过使用几种光学方法，包括使用线性和非线性光谱实现的散射式扫描仪范围内的光谱仪，包括线性和非线性光谱仪，可见，近红外和中红外的波长。 Moiré激子，在线性方案以及共鸣的第二和第三谐波生成实验中，将探测半导体MSL的基本兴奋，对激发态和异源原子原子晶格的对称性敏感。此外，我们的技术将在具有封装的介电或导电层的样品中“在表面下方看”，这是表面扫描技术无法访问的特征。借助我们开发的技术，预计MSL将通过在室温下具有高对比度，非接触和高分辨率的优势可视化。我们新开发的用于纳米成像和纳米光谱的方法将对独特但潜在非常扩展的扭曲异质结构的行为提供根本上的新见解，并且还将适用于其他纳米材料系统（例如钙钛矿），例如，纳米型和外观上的纳米型和外观对纳米级也很高。