Disorder, Topology and Frustration in Quantum Materials

非技术总结该奖项支持理论研究，目的是了解无序对一种名为量子自旋液体的新型物质相的影响。在这个独特的阶段，材料中的电子自旋即使在零温度下也不会像传统磁铁那样建立有序图案，但由于量子力学的特殊性，它们仍然保持液体状。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它在新技术中的潜在应用来看，例如它们有望建造强大的量子计算机。众所周知，在实际材料中，自旋液体相的性质可以在无序存在的情况下被修改或破坏，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提高量子自旋液体相的可辨识性，以及与此相关联的独特量子力学性质。这项理论研究将与实验研究密切合作进行。该奖项还支持与研究项目相关的PI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，特别关注扩大未被充分代表的群体在研究项目中的参与。PI还将组织关于现代凝聚态物理的暑期课程，并与明尼苏达大学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，旨在了解具有强自旋轨道耦合、非平凡拓扑和关联的量子磁体中的受挫和无序效应。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，量子自旋液体相由于其显著的突现特性，包括长程纠缠、拓扑简并和分数激发，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可以用量子自旋液体模型来描述。在真实的量子自旋液体候选材料中，某种程度的无序是不可避免的，这使得有必要了解量子涨落和随机性之间的竞争，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铁中无序效应的理解。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、杂质和键的随机性。这个项目的第二个目标是理解在强自旋轨道耦合和非平凡拓扑存在的情况下，从关联电子的集体行为中产生的新的量子相。该奖项将研究与Kitaev蜂窝模型相近的候选材料和理论模型，更广泛地讲，研究具有强烈各向异性键依赖相互作用的系统。该奖项还支持与研究项目相关的PI的教育和推广活动。研究生和本科生将接受凝聚态物理方面的培训，特别关注扩大未被充分代表的群体在研究项目中的参与。PI还将组织关于现代凝聚态物理的暑期课程，并与明尼苏达大学的魏斯曼美术馆合作，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NSF的法定使命，并通过使用基金会的智力优势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.