CAREER: Electrically tuned topological phase transitions in moire heterostructures

职业：莫尔异质结构中的电调谐拓扑相变

• 批准号: 2237050
• 负责人: Benjamin Feldman
• 金额: $ 80万
• 依托单位: Stanford University
• 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: 2023-03-01 至 2028-02-29
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237050&HistoricalAwards=false
• 关键词: CAREER; Electrically; tuned; topological; phase

Non-technical abstractRecent advances in isolating and manipulating atomically thin materials provide new approaches to tailor material properties. Such two-dimensional systems are both highly sensitive to their environment and they can be stacked so that properties from one layer influence adjacent layers. This project involves combining dissimilar materials so that one both acts as a sensor for and can modulate the electronic properties of the other. In particular, twisting one layer relative to another induces strong interactions between the electrons in them. Modifying the number of electrons in a third nearby layer enables control over the strength of interactions and can change electronic properties such as the distribution of charge at the nanoscale. Furthermore, the reverse process, where the nanoscale charge arrangement imprints a reconfigurable modulation on the third layer, can also lead to exotic quantum behavior. The predicted states may have applications in low-power electronics, fault-tolerant quantum computing, and novel electromagnetic devices. The project also trains undergraduate and graduate students for careers in quantum technology, builds a library of non-technical videos introducing fields of physics, and inspires the next generation of researchers by developing and implementing hands-on high school instructional modules.Technical abstract Stacking van der Waals materials into heterostructures provides unprecedented flexibility to engineer emergent electronic phases. This project investigates hybrid moiré systems in which a twisted transition metal dichalcogenide (TMD) is separated from a bilayer graphene flake by a thin spacer. In this geometry, the graphene both acts as a sensor and can be used to tune among correlated and topological ground states of the twisted TMD. The research focuses on thermodynamic measurements addressing the order and spin/valley character of the ground states and excitations. Primary goals include: 1) exploring the topological phase diagram of twisted TMDs as a function of displacement field; 2) investigation of ferroelectricity and novel Hubbard model geometries; and 3) using the TMD moiré lattice to imprint a reconfigurable periodic potential on the graphene to study Hofstadter butterfly physics. The research is intertwined with parallel educational goals, including development of instructional modules demonstrating key concepts of topology and geometry, and building a library of non-technical videos introducing research subfields. In addition, undergraduates, graduate students, and high school teachers gain direct laboratory experience in the area of van der Waals assembly and low-temperature electronic measurements.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.

非技术性摘要最近在隔离和操纵原子级薄材料方面的进展提供了新的方法来定制材料特性。这样的二维系统都对它们的环境高度敏感，并且它们可以堆叠，使得一层的属性影响相邻层。该项目涉及将不同的材料结合起来，以便其中一种材料既充当另一种材料的传感器，又可以调节另一种材料的电子特性。特别是，相对于另一层扭曲一层会引起其中电子之间的强烈相互作用。修改第三层附近的电子数量可以控制相互作用的强度，并可以改变电子特性，例如纳米级的电荷分布。此外，相反的过程，其中纳米级电荷排列在第三层上压印可重构调制，也可以导致奇异的量子行为。预测的状态可能在低功率电子学、容错量子计算和新型电磁器件中具有应用。该项目还培养本科生和研究生从事量子技术的职业，建立一个介绍物理学领域的非技术视频库，并通过开发和实施实践高中教学模块来激励下一代研究人员。技术摘要将货车德瓦尔斯材料堆叠成异质结构，为工程师设计涌现的电子相提供了前所未有的灵活性。该项目研究混合莫尔系统，其中扭曲的过渡金属二硫属化物（TMD）通过薄间隔物与双层石墨烯薄片分离。在这种几何结构中，石墨烯既充当传感器，又可用于在扭曲TMD的相关和拓扑基态之间进行调谐。研究的重点是解决的顺序和自旋/谷特性的基态和激发的热力学测量。主要目标包括：1）探索扭曲TMD的拓扑相图作为位移场的函数; 2）研究铁电性和新颖的Hubbard模型几何结构; 3）使用TMD莫尔晶格在石墨烯上压印可重构周期势来研究Hofstadter蝴蝶物理。该研究与并行的教育目标交织在一起，包括开发演示拓扑和几何关键概念的教学模块，以及建立一个介绍研究子领域的非技术视频库。此外，本科生、研究生和高中教师还可以获得货车德瓦耳斯装配和低温电子测量领域的直接实验室经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。