Exploring electrodynamics of correlated 2D transition metal dichalcogenides using on-chip terahertz spectroscopy

使用片上太赫兹光谱探索相关二维过渡金属二硫属化物的电动力学

• 批准号: 2311205
• 负责人: Feng Wang
• 金额: $ 59.9万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2311205&HistoricalAwards=false
• 关键词: Exploring; electrodynamics; correlated; 2D; transition

Nontechnical description: Just as we can see the world via electromagnetic waves, one can learn the properties of electronic states in solids by measuring their electromagnetic responses. However, these measurements are sometimes challenging in materials formed by stacks of atomically-thin crystals such as graphene and transition metal dichalcogenides (TMDs). The properties of these materials can give rise to novel quantum states of many electrons, but the characteristic frequencies of such states often fall into the range where the electromagnetic wavelength far exceeds the possible sample size. In this project, the PI develops advanced on-chip THz spectroscopy with integrated sub-wavelength waveguide to study the electromagnetic response of these novel states in TMD heterostructures. The research can advance our fundamental understanding of interacting electrons and lead to new functional THz devices. It can also provide an active learning environment for graduate and undergraduate students to gain interdisciplinary skills. The project engages undergraduate students at UC Berkeley, especially those from underrepresented groups, to drive the frontier of science and technology in the future.Technical description:This project aims to investigate the terahertz electrodynamic responses of correlated quantum phases, such as flat-band metals, correlated insulators, and Wigner crystals, in two-dimensional (2D) transition metal dichalcogenide (TMD) heterostructures. These highly tunable heterostructures have emerged as one of the leading platforms for studying novel states formed by interacting electrons. However, despite the great interest, the electrodynamic properties of these states at their characteristic frequency scales remain largely unknown. In this project, the PI develops advanced on-chip terahertz spectroscopy to study these properties. Specifically, the PI explores three research directions in the project: (1) Studying a new type of 2D plasmon in flat bands with frequency exceeding the upper bound for single electron-hole decay. Such plasmons may have enhanced lifetimes and exhibit properties reflecting the underlying correlated phases. (2) Measuring the full doping evolution of the frequency-dependent conductivity in heterostructures resembling the triangular-lattice Hubbard model, a paradigmatic model of correlated electrons. (3) Investigating the electron vibration modes in Wigner and generalized Wigner crystals, as well as their evolutions across the quantum and thermal melting of these electron crystals. The proposed project can advance our fundamental understanding of the TMD heterostructures and the long-standing correlated electron problem. It also provides an interdisciplinary learning environment for graduate and undergraduate students.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：正如我们可以通过电磁波看到世界一样，可以通过测量其电磁反应来学习固体中电子状态的特性。但是，这些测量有时在由石墨烯和过渡金属二核苷（TMDS）等原子薄晶体（TMDS）等材料中具有挑战性。这些材料的特性会引起许多电子的新量子状态，但是这种状态的特征频率通常落入电磁波长远远超过可能样本量的范围内。在该项目中，PI通过集成的亚波长波导开发了先进的片上THZ光谱，以研究这些新型状态在TMD异质结构中的电磁反应。这项研究可以提高我们对相互作用电子的基本理解，并导致新的功能性THZ设备。它还可以为研究生和本科生提供一个积极的学习环境，以获得跨学科技能。该项目与加州大学伯克利分校的本科生互动，尤其是来自代表性不足的群体的项目，以推动以后的科学和技术领域。技术描述：该项目旨在调查相关量子相的Terahertz电态响应，例如平面金属，相关的绝缘晶体和两层式晶体，并在两层式的跨型物质中进行过量子相关。 （TMD）异质结构。这些高度可调的异质结构已成为研究通过相互作用电子形成的新型状态的领先平台之一。然而，尽管引起了人们的极大兴趣，但这些状态在其特征频率尺度上的电动力特性仍然在很大程度上未知。在该项目中，PI开发了先进的片上terahertz光谱，以研究这些特性。具体而言，PI探讨了该项目中的三个研究方向：（1）在平坦带中研究一种新型的2D等离子体，其频率超过单个电子孔衰变的上限。这种等离子体可能具有增强的寿命，并具有反映基本相关相的特性。 （2）测量类似于三角晶格哈伯德模型的异质结构中频率依赖性电导率的完整掺杂演变，这是相关电子的范式模型。 （3）研究Wigner和广义Wigner晶体中的电子振动模式，以及它们在这些电子晶体的量子和热熔化中的演变。拟议的项目可以提高我们对TMD异质结构和长期相关的电子问题的基本理解。它还为研究生和本科生提供了跨学科的学习环境。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响评估标准，被认为值得通过评估来获得支持。