RUI: CHARGE- AND SPIN-DENSITY STUDY OF EXCHANGE ANISOTROPY IN METAL-ORGANIC QUANTUM MAGNETS

RUI：金属有机量子磁体中交换各向异性的电荷和自旋密度研究

• 批准号: 1306158
• 负责人: Jamie Manson
• 金额: $ 27.6万
• 依托单位: Eastern Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1306158&HistoricalAwards=false
• 关键词: RUI; CHARGE; SPIN; DENSITY; STUDY

****Technical Abstract****The research will focus on two synergistic activities; (a) synthesis of model low-dimensional (1- and 2D) quantum magnets, especially chains and square lattices and (b) examination of charge- and spin-density in those compounds. We endeavor to learn more about the electronic distribution and influences thereof, the exchange pathways in selected Cu(II), Ni(II), and Co(II)-based organic magnets. Our strategy will combine primary structural components assembled by coordinate covalent bonds (CCB's) between M(II) or Ir(IV) cations and diazine ligands [e.g., pyrazine (pyz)], with such ligands being well-known for their good Lewis basicity and ability to act as bridging functionalities and exchange mediators. Secondary interactions based on strong hydrogen bonds (e.g., F---H-O and F---H---F) will provide us with further structural control and an additional magnetic pathway that may dominate M-pyz-M, thus enabling exchange anisotropy. Initially, we will focus on several of the polymers recently developed by our group and then shift toward new systems featuring previously unknown combinations of ancillary ligands. The latter will allow us to systematically perturb electronic states in order to interrogate the salient features of charge- and spin-density distributions in a variety of materials. Undergraduates, from all backgrounds, will carry out the syntheses and assist with data analysis and characterization of samples, travel to state-of-the-art research facilities, and attend/present their work at professional conferences.****Non-Technical Abstract****Metal-organic magnets constitute a major research area in the condensed matter sciences. Their popularity stems from the many synthetic variations that can be made which then allows for systematic investigation of their magnetic properties. Our fundamental research interests lie in using combinations of particular chemical bonds to design architectures of varying dimensionalities so as to tune the important magnetic interactions. In this project, we will utilize X-ray and neutron diffraction methods as well as solid state NMR to study the electron density distributions in designer magnets in order to evaluate the efficiency of certain bond types (e.g. exchange anisotropy) which will depend on the metal ions present. This work could lead to improved materials design and synthesis protocols in order to more effectively prepare multifunctional materials, i.e., those that contain multiple physical properties. Our materials discovery effort will be complemented by extensive characterization and theoretical work. The highly collaborative nature of this project makes use of several national and international user facilities and will provide unique opportunities for undergraduate students to travel with the PI to partake in many of the planned experiments as well as to attend professional conferences. Student involvement in the project will stimulate their growth and enthusiasm, and provide the necessary background to begin graduate work in the future or to go on to careers in the chemical and physical sciences. Mentorship and training of undergraduate students is a high priority of this project.

****技术摘要****该研究将重点关注两项协同活动； (a) 模型低维（1 维和 2 维）量子磁体的合成，特别是链和方形晶格，以及 (b) 检查这些化合物中的电荷和自旋密度。我们努力更多地了解电子分布及其影响，以及选定的 Cu(II)、Ni(II) 和 Co(II) 基有机磁体中的交换途径。我们的策略将结合由 M(II) 或 Ir(IV) 阳离子与二嗪配体 [例如吡嗪 (pyz)] 之间的配位共价键 (CCB) 组装而成的主要结构组件，此类配体以其良好的路易斯碱性以及充当桥接官能团和交换介体的能力而闻名。基于强氢键（例如，F---H-O 和 F---H---F）的二次相互作用将为我们提供进一步的结构控制和可能主导 M-pyz-M 的额外磁路，从而实现交换各向异性。最初，我们将重点关注我们小组最近开发的几种聚合物，然后转向具有以前未知的辅助配体组合的新系统。后者将使我们能够系统地扰动电子态，以探究各种材料中电荷和自旋密度分布的显着特征。来自不同背景的本科生将进行合成并协助数据分析和样品表征，前往最先进的研究设施，并参加专业会议/在专业会议上展示他们的工作。****非技术摘要****金属有机磁体构成了凝聚态科学的主要研究领域。它们的受欢迎源于可以进行许多合成变体，从而可以系统地研究它们的磁性。我们的基础研究兴趣在于利用特定化学键的组合来设计不同维度的结构，从而调整重要的磁相互作用。在这个项目中，我们将利用 X 射线和中子衍射方法以及固态 NMR 来研究设计磁体中的电子密度分布，以评估某些键类型（例如交换各向异性）的效率，这取决于存在的金属离子。这项工作可以改进材料设计和合成方案，以便更有效地制备多功能材料，即包含多种物理特性的材料。我们的材料发现工作将得到广泛的表征和理论工作的补充。该项目的高度协作性质利用了多个国内和国际用户设施，并将为本科生提供独特的机会，与 PI 一起旅行，参与许多计划中的实验以及参加专业会议。学生参与该项目将激发他们的成长和热情，并为未来开始研究生工作或继续从事化学和物理科学的职业提供必要的背景。本科生的指导和培训是该项目的重中之重。