CAREER: Band-Topology of Multipolar Magnetic Excitations

该奖项部分由2021年美国救援计划法案（公法117-2）资助。该奖项支持旨在发现和理解磁性量子材料的奇异性质的理论研究。考虑电子的集体行为，而不是检查电子的单个属性，揭示了物质的许多显着特性，包括磁性的产生。电子的自旋和轨道自由度的相互作用可以产生与原始成分截然不同的新状态，并且与技术应用具有很大的相关性。这个项目的重点是了解这些物质紧急状态的条件，并旨在发现新的特征，以促进它们的实验检测和控制。具体来说，本研究整合了扎根于现代拓扑和对称性概念的理论工具来表征新的磁态。此外，它还建立了理论描述与材料对不同实验探针的响应之间的联系。与实验组合作考虑真实材料是研究设计的一个组成部分。这项研究的结果为建立在磁和光控制基础上的低能耗可重构器件开辟了新的途径。该奖项还支持外展工作，以缩小服务不足和边缘化社区学生的STEM机会差距。这将在从小学到研究生院的多个教育层次上得到解决，旨在激发人们对科学的兴趣，建立科学家的身份，缩小准备差距，并提高代表性不足的少数民族的保留率。特别是，PI将启动暑期课程、物理训练营和两年一次的研究生暑期学校，并加入她所在机构针对中学生的外展活动，以提高他们对现有机会的认识，并帮助他们展望高等教育的未来。该奖项支持旨在发现和理解量子磁体的奇异特性的理论研究。具有多分量局部希尔伯特空间的磁性材料具有实现新型拓扑态的非凡潜力。他们承认了非常规的多极自由度，并呼吁用一种一般化的方法来表征它们的拓扑结构和实验特征。特别地，本研究将探讨由自旋、轨道和晶格自由度组合产生的扩大的局部希尔伯特空间如何提供一个内部结构来保护非平凡拓扑。此外，它将揭示他们如何实现基于磁电效应，表面选择性光学响应和独特霍尔信号的拓扑边界模式的新型实验探针。本研究结果将促进我们对多极磁激励带拓扑结构的理解，并为其检测和操作发现独特的实验指纹。此外，它们将与广泛的玻色子系统直接相关，包括但不限于光子、声学和机械晶格以及人工磁子超材料。该奖项还支持外展工作，以缩小服务不足和边缘化社区学生的STEM机会差距。这将在从小学到研究生院的多个教育层次上得到解决，旨在激发人们对科学的兴趣，建立科学家的身份，缩小准备差距，并提高代表性不足的少数民族的保留率。特别是，PI将启动暑期课程、物理训练营和两年一次的研究生暑期学校，并加入她所在机构针对中学生的外展活动，以提高他们对现有机会的认识，并帮助他们展望高等教育的未来。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。

This award is funded in part under the American Rescue Plan Act of 2021 (Public Law 117-2).NONTECHNICAL SUMMARYThis award supports theoretical research aimed at the discovery and understanding of exotic properties of magnetic quantum materials. Instead of examining the individual attributes of electrons, considering their collective behavior reveals many remarkable properties of matter, including the generation of magnetism. The interplay of the electrons' spin and orbital degrees of freedom can produce novel states that behave very differently from the original constituents and bear great relevance for technological applications. This project focuses on understanding the conditions for such emergent states of matter and aims to uncover new features that facilitate their experimental detection and control. Specifically, this research integrates theoretical tools rooted in the modern concepts of topology and symmetries to characterize novel magnetic states. Furthermore, it establishes a connection between the theoretical description and the materials' responses to different experimental probes. Considering real materials in collaboration with experimental groups is an integral part of the research design. The results of this study can open new routes to low-energy consuming reconfigurable devices that build on magnetism and optical control. This award also supports outreach efforts to decrease the STEM opportunity gap of students from underserved and marginalized communities. This will be addressed on multiple levels of education, from elementary to graduate school, aiming to spark interest in sciences, build scientist identity, reduce the preparation gap, and improve the retention of underrepresented minorities. In particular, the PI will initiate summer programs, a physics Bootcamp, and a biennial graduate summer school and join an existing outreach activity at her institution targeting middle school students to promote awareness of existing opportunities and to help them visualize a future in higher education.TECHNICAL SUMMARYThis award supports theoretical research aimed at the discovery and understanding of the exotic properties of quantum magnets. Magnetic materials endowed with a multi-component local Hilbert space have an extraordinary potential for realizing novel topological states. They admit unconventional multipole degrees of freedom, calling for a generalized approach to characterize their topology and experimental signatures. In particular, this research will explore how the enlarged local Hilbert spaces originating from the combination of spin, orbital, and lattice degrees of freedom can provide an internal structure to protect the nontrivial topologies. Furthermore, it will reveal how they can realize novel experimental probes for topological boundary modes based on the magneto-electric effect, surface-selective optical responses, and distinctive Hall signals. The results of this study will advance our understanding of the band-topology of multipole magnetic excitations and uncover unique experimental fingerprints for their detection and manipulation. Moreover, they will be directly relevant for a wide range of bosonic systems, including but not limited to photonic, acoustic, and mechanical lattices and artificial magnonic metamaterials.This award also supports outreach efforts to decrease the STEM opportunity gap of students from underserved and marginalized communities. This will be addressed on multiple levels of education, from elementary to graduate school, aiming to spark interest in sciences, build scientist identity, reduce the preparation gap, and improve the retention of underrepresented minorities. In particular, the PI will initiate summer programs, a physics Bootcamp, and a biennial graduate summer school and join an existing outreach activity at her institution targeting middle school students to promote awareness of existing opportunities and to help them visualize a future in higher education.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.