Collaborative Research: Probing quasiparticle excitations in TMDC Moiré superlattices for revealing and understanding novel two-dimensional correlated phases

合作研究：探测 TMDC 莫尔超晶格中的准粒子激发，以揭示和理解新颖的二维相关相

• 批准号: 2103842
• 负责人: Xiaofeng Qian
• 金额: $ 21.5万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103842&HistoricalAwards=false
• 关键词: Collaborative; Research; Probing; quasiparticle; excitations

Non-technical abstract:Thanks to the development of two-dimensional (2D) atomic crystals, researchers have managed to create a new kind of periodic lattice that arises from the interference of two vertically stacked 2D atomic lattices. The existence of this so called "moire superlattice", has been theoretically predicted and experimentally demonstrated. In this collaborative project, the research team studies a family of such moire superlattices made from transition metal dichalcogenides (TMDC). The team aims at understanding the key questions of how semiconducting TMDC monolayers turn into unconventional insulators, magnets, or even superconductors when stacked together vertically, by probing the dynamics of the periodic lattices, the charge carriers, and the magnetic moments in these TMDC stacked structures. The project is further integrated with education and outreach activities to recruit and mentor underrepresented and first-generation students, present demo experiments and tutorials to K-12 students, and introduce the background and results from collaborative research to the general public. These activities involve a wide group of participants and promote science, technology, and engineering among K-12 students and the public.Technical abstract:The formation of moire superlattice by either lattice mismatch or angular misalignment between two atomically thin crystals has been experimentally demonstrated as a powerful way to design and engineer electronic properties of 2D systems. One particular outstanding example is the small twist-angle TMDC moire superlattices, showing a wealth of strongly correlated electronic phases that are absent in the individual composing TMDC monolayers. In this collaborative project, the research goal is to develop a comprehensive understanding on these emergent correlated phases in TMDC moire superlattices. The focus is to investigate the collective phonon, charge, and magnon excitations of these correlated phases by using an integrated optical spectroscopy experiment and first-principles theory method. Specifically, the research team fabricates TMDC moire superlattices, performs time- and frequency-domain dynamic measurements using time-resolved and Raman optical spectroscopy, and carries out theoretical calculations to guide the experimental design and interpret the experimental results. The success of this project not only opens a new pathway to better understand emergent correlated physics in 2D systems, but also expands the platform to explore strongly correlated physics in general.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要：由于开发了二维原子晶体，研究人员设法创建了一种新型的定期晶格，这是由于两个垂直堆积的2D原子晶格的干扰而产生的。理论上已经预测和实验证明了这种所谓的“摩尔超级晶格”的存在。在这个合作项目中，研究小组研究了由过渡金属二分法元素（TMDC）制成的这样的Moire超级晶格家族。该团队的目的是了解半导体TMDC单层如何通过垂直堆叠在一起时如何变成非常规的绝缘体，磁铁，甚至是超导体，甚至通过探测这些TMDC堆叠式堆叠结构中的磁矩，以及磁性磁矩的动力。该项目进一步与教育和外展活动相结合，以招募和导师的代表性不足和第一代学生，向K-12学生提供演示实验和教程，并向公众介绍合作研究的背景和结果。这些活动涉及K-12学生和公众之间的一系列参与者，并促进科学，技术和工程学。技术摘要：通过晶格不匹配或两种原子上薄晶体之间的Moire Super突变素形成，已被实验证明是一种有力的设计和设计2D系统的电子属性的方法。一个特别的杰出例子是小的扭曲角tmdc moire超级晶格，显示了组成TMDC单层中不存在的大量密切相关的电子相。在这个协作项目中，研究目标是对TMDC Moire超级晶格中这些新兴相关阶段的全面了解。重点是通过使用集成的光谱实验和第一原理理论方法来研究这些相关相的集体声子，电荷和镁激发。具体而言，研究团队制造TMDC Moire超级晶格，使用时间分辨和拉曼光学光谱进行时间和频域动态测量，并进行理论计算以指导实验设计并解释实验结果。该项目的成功不仅开辟了一条新的途径，以更好地了解2D系统中的新兴相关物理，而且还扩展了平台，以探索一般的物理学强烈相关的物理。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响审查标准来通过评估来获得支持的。

项目成果

Generalized Wilson loop method for nonlinear light-matter interaction

• DOI: 10.1038/s41535-022-00472-4
• 发表时间: 2022-06
• 期刊: npj Quantum Materials
• 影响因子: 5.7
• 作者: Hua Wang;Xiuyu Tang;Haowei Xu;Ju Li;Xiaofeng Qian