Investigation of Strongly Correlated Itinerant Magnets and Potential Quantum Spin Liquids

先进的磁性材料对许多当前和未来的技术至关重要，这些技术对我们国家的能源安全至关重要。其中包括电动汽车、风力涡轮机、磁性冰箱和高密度数据存储设备。这些技术的改进依赖于我们通过发展对晶体结构和磁性行为之间相关性的基本理解来发现新的和优化现有磁性材料的能力。在材料研究部固态与材料化学项目的支持下，该研究项目旨在探索磁性能对晶体和电子结构的细微变化高度敏感的材料。这种固体在微小的外部扰动（例如温度或压力）下会表现出磁性行为的突然变化，并且可以为在较低功率下运行并表现出较高能量转换效率的设备提供途径。该项目将为研究生和本科生提供固态化学、材料合成、晶体学、磁学和能量转换技术方面的培训。研究小组还将开发一个全面的开放访问的强相关磁性材料在线数据库。PI在让代表性不足的群体和本科生参与研究工作方面有着良好的记录，并将在他的研究和推广活动中继续保持这种做法。技术概述流动磁性是高性能永磁体和软磁材料的基础。本研究项目侧重于两类磁性材料的研究，这两类材料都利用了电子能带结构中的强相关性，从而转化为非常规的磁性行为。将研究三元砷化物和硼化物金属间化合物的磁性对晶体和电子结构特性的敏感性。后者将通过明智地改变化学成分或施加外部压力而受到干扰。化学和物理扰动都能引起价的波动，这将转化为这些材料所表现出的磁性的强烈变化。将密切关注3d-4f磁交换的性质，以制定对每组材料中晶格间磁耦合类型的一般期望。研究小组还将研究具有低维结构的三元硒化物，这种结构会导致强磁挫折。据预测，这种材料可以避免长程磁有序，从而导致奇异量子态，例如自旋液体或霍尔丹间隙系统。这些研究活动将为研究生和本科生提供材料合成、结构和磁性研究以及电子能带结构研究等多方面的训练。

NON-TECHNICAL SUMMARYAdvanced magnetic materials are crucial to a number of current and upcoming technologies that are critical to our nation's energy security. Among these are electric vehicles, wind turbines, magnetic refrigerators, and high-density data storage devices. The improvement of such technologies relies on our ability to discover new and optimize existing magnetic materials by developing fundamental understanding of correlations between crystal structure and magnetic behavior. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, this research project targets the exploration of materials whose magnetic properties are highly sensitive to subtle changes in the crystal and electronic structures. Such solids will demonstrate abrupt changes in the magnetic behavior upon minor external perturbations (e.g., temperature or pressure) and can offer pathways to devices that operate at lower powers and exhibit higher energy-conversion efficiencies. The project will provide training for graduate and undergraduate students in solid state chemistry, materials synthesis, crystallography, magnetism, and energy-conversion technologies. The research team will also develop a comprehensive open-access online database for strongly correlated magnetic materials. The PI has a proven track-record of involving underrepresented groups and undergraduate students in research endeavors, and will continue to maintain this practice in his research and outreach activities.TECHNICAL SUMMARYItinerant magnetism provides the foundation for high-performance permanent and soft magnetic materials. This research project focuses on the investigation of two classes of magnetic materials, both of which leverage strong correlations in the electronic band structure that translates into unconventional magnetic behaviors. Ternary arsenide and boride intermetallics will be investigated vis-a-vis the sensitivity of their magnetic properties to peculiarities of crystal and electronic structures. The latter will be perturbed via judicious changes in chemical composition or application of external pressure. Both chemical and physical perturbations can induce valence fluctuations that will translate into strong changes in magnetism demonstrated by these materials. A close attention will be paid to the nature of 3d-4f magnetic exchange to formulate general expectations for the type of interlattice magnetic coupling in each group of materials. The research team will also investigate ternary selenides with low-dimensional structures that result in strong magnetic frustration. Such materials are predicted to avoid long-range magnetic ordering, thus leading to exotic quantum states, e.g., spin liquids or Haldane-gap systems. The proposed research activities will provide versatile training to graduate and undergraduate students in materials synthesis, investigation of structural and magnetic properties, and studies of the electronic band structure.