Investigation of topological electronic states in atomic layered materials and heterostructures

原子层状材料和异质结构中的拓扑电子态研究

• 批准号: 2004701
• 负责人: Yongtao Cui
• 金额: $ 34万
• 依托单位: University of California-Riverside
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2004701&HistoricalAwards=false
• 关键词: Investigation; topological; electronic; states; atomic

Non-technical Abstract:Conventional conductors and insulators are distinguished by their abilities to conduct electricity. Topological insulators are a new class of materials which combine an insulating interior with conducting surfaces. Their unique electronic properties can enable new generation of quantum technology such as quantum computers and energy efficient electronics. A recently discovered material, WTe2, exhibits such topological behavior in a single layer form. In this 2D topological insulator system, electrical current can only flow along the edges of the sample. This project investigates the electrical properties both in the interior bulk and at edges of monolayer WTe2, aiming to understand the connection between the topological bulk states and the conducting edges and to develop new methods to manipulate these properties by stacking monolayer WTe2 on other 2D materials. The research team also builds an experimental workflow to effectively screen candidate topological materials predicted by theory, which could potentially lead to discovery of new 2D topological systems. The project is integrated with education activities to attract undergraduate students to research and train them in advanced electronics hardware and development of new instrumentation.Technical Abstract:This project aims to investigate topological physics in 2D systems based on atomic layered materials, with a focus on a recently discovered 2D topological insulator, monolayer WTe2. The research employs a range of electrical characterization techniques to probe the electronic properties of the topological states, including local conductivity by microwave impedance microscopy, chemical potential by electrostatic force microscopy, and thermodynamic density of states by quantum capacitance measurement. The goal is to understand the nature of the bulk electronic states including the effect of interaction on the topological properties. The project also explores heterostructures of monolayer WTe2 with other 2D materials in order to manipulate the topological properties in monolayer WTe2. The research team further develops an effective experimental method to screen candidate materials that are predicted to be 2D topological insulators. The approach involves integration of fabrication and characterization techniques suitable for the study of air-sensitive materials and develops a workflow that minimizes sample fabrication to enhance throughput. Graduate and undergraduate students are involved in the development of the experimental methods which provides a comprehensive training in device fabrication, instrumentation design, and data analysis.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：传统的导体和绝缘子的传导能力。拓扑绝缘子是一种新的材料，将绝缘内部和导电表面结合在一起。它们独特的电子特性可以使新一代的量子技术（例如量子计算机和节能电子产品）。最近发现的材料WTE2以单层形式表现出这种拓扑行为。在这个2D拓扑绝缘体系统中，电流只能沿着样品的边缘流动。该项目研究了单层WTE2的内部和边缘的电气性能，旨在了解拓扑散装状态和导电边缘之间的连接，并开发新的方法来通过在其他2D材料上堆叠单层WTE2来操纵这些性质。研究团队还建立了一个实验性工作流程，以有效筛选理论预测的候选拓扑材料，这可能会导致发现新的2D拓扑系统。该项目与教育活动集成在一起，以吸引本科生来研究和培训他们在高级电子硬件和新仪器开发中进行培训。技术摘要：该项目旨在调查基于原子分层材料的2D系统中的拓扑物理学，重点是最近发现的2D拓扑绝缘子Monolayer WTE2。该研究采用一系列电气表征技术来探测拓扑状态的电子性质，包括微波阻抗显微镜局部电导率，通过静电力显微镜进行化学电位以及通过量子电容测量的态热力学密度。目的是了解批量电子状态的性质，包括相互作用对拓扑特性的影响。该项目还使用其他2D材料探索单层WTE2的异质结构，以操纵单层WTE2中的拓扑特性。研究团队进一步开发了一种有效的实验方法，用于筛选候选材料，该方法预计为2D拓扑绝缘子。该方法涉及整合制造和表征技术，适合于研究空气敏感材料，并开发出一种工作流，从而最大程度地减少样品制造以增强吞吐量。研究生和本科生参与了实验方法的开发，该方法在设备制造，仪器设计和数据分析方面提供了全面的培训。该奖项反映了NSF的法定任务，并被认为值得通过基金会的智力优点进行评估来支持，并具有更广泛的影响。

项目成果

Determination of the Spin Axis in Quantum Spin Hall Insulator Candidate Monolayer WTe2

• DOI: 10.1103/physrevx.11.041034
• 发表时间: 2020-10
• 期刊: Physical Review X
• 影响因子: 12.5
• 作者: Wenxuan Zhao;E. Runburg;Z. Fei;J. Mutch;P. Malinowski;Bosong Sun;Xiong Huang;D. Pesin

Evidence for equilibrium exciton condensation in monolayer WTe2

• DOI: 10.1038/s41567-021-01427-5
• 发表时间: 2021-12-23
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Sun, Bosong;Zhao, Wenjin;Cobden, David H.
• 通讯作者: Cobden, David H.