Optical Study of Electron Correlation in Graphene-Based Moire Superlattices

石墨烯基莫尔超晶格中电子相关性的光学研究

• 批准号: 2225925
• 负责人: Long Ju
• 金额: $ 60万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2225925&HistoricalAwards=false
• 关键词: Optical; Study; Electron; Correlation; Graphene

Non-technical description:Superlattices, stacks of multiple layers of materials with different compositions, formed from two-dimensional (2D) materials host incredible flexibilities in engineering material properties through controlling the stacking order, the twist angle, and tuning of the electron density. Such engineered materials have remarkable electrical and optical properties that do not exist in individual 2D materials. This project advances our understanding of carbon-based materials, thus enabling new design principles of quantum materials and their device applications for quantum science and technology. This project helps graduate and undergraduate students from under-represented groups bridge the gap between textbook learning and scientific research by providing interdisciplinary scientific experience. It stimulates the interest of K-12 students in 2D materials and the fields of science, technology, engineering, and mathematics, training the future workforce. This project also enriches the experimental capabilities of the user facility at the NSF-funded National High Magnetic Field Laboratory and provides technical support to users in the broad quantum materials research community.Technical description:This project address fundamental questions regarding electron correlation in the moiré superlattices involving few-layer graphene and hexagonal boron nitride. The research team uses this new material platform to engineer and study superconductivity, Mott insulator, and magnetic ground states— physics that were previously realized in conventional strongly correlated materials such as high-Tc superconductors. The proposed research advances the field of 2D materials through the following innovations. (1) It generates the first infrared spectroscopy data of several graphene-based moiré superlattices and reveals critical energy scales relevant to electron correlation. Such information forms the basis of accurate theoretical modeling and better interpretation of already discovered correlation phenomena. (2) It develops unique optical spectroscopy and microscopy tools that help fabricate new device structures with widely tunable twist angle, charge density and band structures. By performing electron transport measurement on these devices, the research team explores the limit of electron correlation such as the superconducting transition temperature Tc. (3) It systematically studies the connection and difference between correlation phenomena in moiré and non-moiré systems of 2D materials. This helps understand the exact role of moiré superlattice for better engineering of electron correlation in stacks of 2D materials.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.

非技术描述：超晶格，由二维（2D）材料形成的具有不同成分的多层材料的堆叠，通过控制堆叠顺序，扭转角和电子密度的调整，在工程材料特性方面具有令人难以置信的灵活性。这种工程材料具有在单个2D材料中不存在的显著的电学和光学特性。该项目推进了我们对碳基材料的理解，从而使量子材料的新设计原理及其在量子科学和技术中的器件应用成为可能。该项目通过提供跨学科的科学经验，帮助来自代表性不足群体的研究生和本科生弥合教科书学习和科学研究之间的差距。它激发了K-12学生对2D材料和科学，技术，工程和数学领域的兴趣，培养了未来的劳动力。该项目还丰富了NSF资助的国家强磁场实验室的用户设备的实验能力，并为广泛的量子材料研究社区的用户提供技术支持。技术说明：该项目解决了涉及少层石墨烯和六方氮化硼的莫尔超晶格中电子相关的基本问题。研究团队使用这种新材料平台来设计和研究超导性，莫特绝缘体和磁基态-以前在传统的强相关材料中实现的物理学，如高温超导体。拟议的研究通过以下创新推进了2D材料领域。(1)它生成了几个石墨烯基莫尔超晶格的第一个红外光谱数据，并揭示了与电子相关的临界能量尺度。这些信息构成了准确的理论建模和更好地解释已经发现的相关现象的基础。(2)它开发独特的光谱和显微镜工具，帮助制造具有广泛可调扭曲角，电荷密度和能带结构的新器件结构。通过对这些设备进行电子传输测量，研究小组探索了电子相关性的极限，如超导转变温度Tc。(3)系统地研究了二维材料云纹和非云纹系统中相关现象的联系和区别。这有助于理解莫尔超晶格在2D材料堆中更好地工程化电子相关性方面的确切作用。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。