Disorder, Topology and Frustration in Quantum Materials

该奖项支持理论研究，旨在了解一种称为量子自旋液体的物质的新阶段的无序影响。在这个独特的阶段，即使在零温度下，材料中的电子自旋也不会像在传统磁铁中那样建立有序的模式，而是由于量子力学的特殊性而保持液体状。几十年来，这一阶段一直是凝聚态物理学的中心主题，无论是从基本角度还是从其在新技术中的潜在应用角度来看，比如它们对构建强大量子计算机的承诺。众所周知，在实际材料中，自旋液相的性质可以在无序存在的情况下被改变或破坏，例如由于缺少原子或杂质而导致的原子缺陷。在这个项目中，PI和她的团队将研究真实材料中不同类型的无序如何抑制或增强量子自旋液相的可辨性，以及与此相相关的独特量子力学特性。这项理论研究将与实验研究密切合作进行。该奖项还支持PI与研究项目相关的教育和外展活动。研究生和本科生将接受凝聚态物理方面的培训，特别关注扩大研究项目中代表性不足群体的参与。PI还将组织关于现代凝聚态物理的暑期学校，并与明尼苏达大学的魏斯曼艺术博物馆合作，为本科生开发一个结合艺术和科学学科的新项目。该奖项支持理论研究，旨在理解具有强自旋-轨道耦合，非平凡拓扑和相关性的量子磁体中的挫折和无序效应。这一广阔的领域最近在理论和实验方面都取得了重大进展。特别是量子自旋液相，由于其显著的涌现特性，包括远程纠缠、拓扑简并和分数化激发，一直是凝聚态物理学的中心主题之一。越来越多的候选磁性材料被认为是由量子自旋液体模型充分描述的。在实际的量子自旋液体候选材料中，一定程度的无序是不可避免的，这就需要理解量子涨落与随机性之间的竞争，以揭示其低能相的真实性质。该项目的主要目标之一是扩大目前对量子磁体中无序效应的理解。PI将研究量子自旋液体如何响应各种形式的无序，如位错、空位、杂质和键随机性。该项目的第二个目标是了解在强自旋轨道耦合和非平凡拓扑存在下相关电子的集体行为所产生的新量子相。PI将研究候选材料和接近Kitaev蜂窝模型的理论模型，更一般地说，研究具有强各向异性键依赖相互作用的系统。该奖项还支持PI与研究项目相关的教育和外展活动。研究生和本科生将接受凝聚态物理方面的培训，特别关注扩大研究项目中代表性不足群体的参与。PI还将组织关于现代凝聚态物理的暑期学校，并与明尼苏达大学的魏斯曼艺术博物馆合作，为本科生开发一个结合艺术和科学学科的新项目。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 research with an aim to understand the effects of disorder in a novel phase of matter called the quantum spin liquid. In this unique phase, electron spins in a material do not establish ordered patterns, even at zero temperature, as they normally do in conventional magnets, but remain liquid-like due to the peculiarities of quantum mechanics. This phase has been a central theme in condensed matter physics for decades, both from a fundamental perspective and in terms of its potential applications in novel technologies, such as their promise for building robust quantum computers. It is known that the properties of the spin liquid phase in real materials can be modified or destroyed in the presence of disorder, such as atomic imperfections due to missing atoms or impurities. In this project, the PI and her team will investigate how different types of disorder in real materials can suppress or enhance the discernibility of quantum spin liquid phase and the unique quantum mechanical properties associated with this phase. This theoretical research will be conducted in close collaboration with experimental studies.This award also supports the PI's educational and outreach activities that are linked to the research projects. Graduate and undergraduate students will be trained in condensed matter physics with a particular eye toward broadening participation of underrepresented groups in the research projects. The PI will also organize summer schools on modern condensed matter physics and collaborate with the Weisman Art Museum at the University of Minnesota to develop a new program for undergraduate students that combines artistic and scientific disciplines. TECHNICAL SUMMARY This award supports theoretical research with an aim to understand frustration and disorder effects in quantum magnets with strong spin-orbit coupling, non-trivial topology and correlations. This broad field has recently experienced significant advances in both theory and experiment. In particular, the quantum spin liquid phase has been one of the central themes in condensed matter physics, owing to their remarkable emergent properties, including long-range entanglement, topological degeneracy and fractionalized excitations. A growing number of candidate magnetic materials are believed to be adequately described by quantum spin liquid models. Some level of disorder is inevitable in real quantum spin liquid candidate materials, which makes it necessary to understand the competition between quantum fluctuations and randomness in order to unveil the true nature of their low-energy phase. One of the main goals of this project is to expand the current understanding of the effects of disorder in quantum magnets. The PI will study how quantum spin liquids respond to various forms of disorder, such as dislocations, vacancies, impurities, and bond randomness. A second goal of this project is to understand novel quantum phases arising from a collective behavior of correlated electrons in the presence of strong spin-orbit coupling and non-trivial topology. The PI will study both candidate materials and theoretical models proximate to the Kitaev honeycomb model and, more generally, on systems with strongly anisotropic bond-dependent interactions.This award also supports the PI's educational and outreach activities that are linked to the research projects. Graduate and undergraduate students will be trained in condensed matter physics with a particular eye toward broadening participation of underrepresented groups in the research projects. The PI will also organize summer schools on modern condensed matter physics and collaborate with the Weisman Art Museum at the University of Minnesota to develop a new program for undergraduate students that combines artistic and scientific disciplines.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.