Doping Effects on Excited-State Properties of Two-Dimensional Moiré Crystals

该奖项支持旨在促进对二维云纹晶体中电子之间相互作用的理解的理论和计算研究以及教育活动，二维云纹晶体是由两个原子层以扭曲角度堆叠而形成的新兴量子材料。这些扭曲的结构提供了一个周期电位，限制了电子并显著增强了它们的相互作用，从而产生了新的电子和光学性质，如超导性、磁性、金属/绝缘体跃迁和高效的光吸收/发射。在这个项目中，PI计划通过从晶体中添加或提取电子来有效地控制这种限制效应。由于莫尔晶体独特的二维特性，PI期望电子数量的微小变化可以极大地调节约束势，并随后以数量级改变电导率、磁性和光-物质相互作用。为了准确计算这些独特的电子相互作用，PI将开发理论模型并在高性能仿真软件包中实现它们。预测的可调谐的多电子相互作用以及电子和光学性质可能会导致新型电子器件、可编程光子发射器/探测器和无耗散电子状态的实现，这些都有望实现节能量子信息应用。除了研究工作外，该奖项还支持研究生和本科生作为下一代科学和工程劳动力的培训和教育。招收女生和少数族裔学生，通过大规模模拟探索量子材料的新特性和应用。PI还将为本科生开发一门基于模拟的凝聚态物理课程。该奖项支持一项综合研究、教育和推广计划，重点探索二维云纹晶体的掺杂依赖激发态特性。由云纹图案形成的周期性量子约束有望捕获准粒子和激子，并实现可编程传输和光学应用的相同量子点阵列。此外，这些云纹势可以增强范霍夫奇点，并呈现不寻常的多体物理，如莫特绝缘相、维格纳晶体、非常规超导性、激子凝聚和拓扑秩序。所有这些期望的现象和应用本质上是由准粒子和激子决定的，它们是由许多电子相互作用形成的激发态。在这个项目中，PI将计算对多电子筛选的增强掺杂效应，从而计算激发态，作为调整莫尔势，多体物理和拓扑顺序的有效手段。PI将开发第一线多体微扰理论方法来捕捉云纹等离子体激元和激发态之间的耦合，用于计算掺杂二维云纹材料中的准粒子和激子。通过掺杂窄间隙拓扑云纹晶体来实现平面激子带和激子绝缘体的新机会也将被探讨。除了研究工作外，该奖项还支持研究生和本科生作为下一代科学和工程劳动力的培训和教育。招收女生和少数族裔学生，通过大规模模拟探索量子材料的新特性和应用。PI还将为本科生开发一门基于模拟的凝聚态物理课程。该奖项反映了美国国家科学基金会的法定使命，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。

NONTECHNICAL SUMMARYThis award supports theoretical and computational research and educational activities that aim to advance the understanding of interactions between electrons in two-dimensional Moire crystals, which are emerging quantum materials formed by stacking two atomic layers with a twisting angle. These twisted structures render a periodic potential that confine electrons and significantly enhance their interactions, giving rise to new electronic and optical properties, such as superconductivity, magnetism, metal/insulator transitions, and highly efficient optical absorption/emission. In this project, the PI plans to efficiently control this confinement effect by adding or extracting electrons from the crystal. Because of the unique two dimensionality of Moire crystals, the PI expects that a small variation in the number of electrons can dramatically tune the confinement potential and subsequently change the electrical conductance, magnetism, and light-matter interactions by orders of magnitude. To accurately calculate these unique electronic interactions, the PI will develop theoretical models and implement them in high-performance simulation packages. The predicted tunable many-electron interactions and electronic and optical properties can potentially lead to the realization of novel electronic devices, programable photon emitters/detectors, and dissipationless electronic states that are promising for energy-efficient quantum-information applications.In addition to the research efforts, this award also supports the training and education of graduate and undergraduate students as the next-generation scientific and engineering workforce. Female and minority students will be recruited to engage in exploring new properties and applications of quantum materials by large-scale simulations. The PI will also develop a simulation-based condensed matter physics course for undergraduate students.TECHNICAL SUMMARYThis award supports an integrated research, education, and outreach program focusing on exploring doping dependent excited-state properties of two-dimensional Moire crystals. The periodic quantum confinement formed by Moire patterns is expected to trap quasiparticles and excitons and to realize arrays of identical quantum dots for programmable transport and optical applications. Moreover, these Moire potentials can enhance van Hove singularities and render unusual many-body physics, such as the Mott insulating phase, Wigner crystals, unconventional superconductivity, exciton condensation, and topological orders. All these desired phenomena and applications are essentially decided by quasiparticles and excitons, which are excited states formed by many-electron interactions. In this project, the PI will calculate the enhanced doping effects on many-electron screening and hence the excited states, functioning as an efficient means of tuning Moire potentials, many-body physics, and topological orders. The PI will develop first-principles many-body perturbation theory methods to capture the coupling between Moire plasmons and excited states for calculating quasiparticles and excitons in doped two-dimensional Moire materials. New opportunities to realize flat exciton bands and exciton insulators by doping narrow-gap topological Moire crystals will also be investigated. In addition to the research efforts, this award also supports the training and education of graduate and undergraduate students as the next-generation scientific and engineering workforce. Female and minority students will be recruited to engage in exploring new properties and applications of quantum materials by large-scale simulations. The PI will also develop a simulation-based condensed matter physics course for 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.