Investigation of Magnetism in Discrete Rare-Earth Clusters and Low Dimensional Solids

离散稀土团簇和低维固体的磁性研究

• 批准号: 0606269
• 负责人: Timothy Hughbanks
• 金额: $ 33万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-11-15 至 2010-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0606269&HistoricalAwards=false
• 关键词: Investigation; Magnetism; Discrete; Rare; Earth

This project aims to investigate magnetism in discrete rare-earth clusters and low dimensional solids. In magnetic materials, 4f moments provide intrinsic magnetic anisotropy that is central to the function of hard permanent magnets. The goal is to investigate the interplay between the electronic features that are characteristic of the delocalized (5d and 6s) electrons in 2-, 1-, and 0-dimensional (cluster) compounds and the localized (magnetic) 4f electrons. Studies of rare-earth clusters and low-dimensional solids that integrate synthesis, properties measurements, and limited use of computational methods for interpretation and understanding of properties will be emphasized. The project builds on the results of exploratory synthetic investigations of rare-earth solids (mostly halides) that have been ongoing for three decades, but which have so far seen limited systematic investigation of magnetic properties and almost no theoretical analysis. Since low-dimensional compounds often exhibit structural instabilities (e.g., Peierls and Jahn-Teller distortions in 1- and 0-dimensional systems, charge-density wave phenomena in 2-D), the possibility of structural transitions coincident with magnetic transitions will be explored, thus yielding first-order magnetic transitions characteristic of giant-magnetocaloric materials.The lanthanide elements play an important role in a variety of technologies - many, perhaps most, of which rely on the unique role that their f-electrons play in their chemistry. Their optical properties play an essential role in lanthanide-containing laser materials. In magnetic materials, lanthanides are central to the function of hard permanent magnets. In this project, we will investigate whether lanthanide-containing molecules might function as molecular magnets - the smallest conceivable 'bar-magnets'. If so, lanthanide-containing molecules could help provide nanotechnological information storage capacity that would far outstrip current hard-drive technologies. Also of interest are lanthanide-containing materials whose magnetic properties, structural properties, and thermal properties are coupled. Such materials are promising in a new generation of magnetic refrigerators with efficiencies that exceed current refrigeration technology. The training of students, undergraduate and graduate, as well as postdoctoral fellows, to compete well for industrial and academic positions in areas such as these continues to be a priority.

本项目旨在研究离散稀土团簇和低维固体中的磁性。在磁性材料中，4f矩提供了磁性各向异性，这是硬永磁体功能的核心。目的是研究2维、1维和0维（团簇）化合物中的离域（5d和6s）电子特征与定域（磁性）4f电子之间的相互作用。将强调稀土团簇和低维固体的研究，这些研究整合了合成、性质测量和有限使用的计算方法来解释和理解性质。该项目建立在对稀土固体（主要是卤化物）的探索性合成研究的基础上，这些研究已经进行了30年，但迄今为止，对磁性的系统研究有限，几乎没有理论分析。由于低维化合物通常表现出结构不稳定性（例如，1维和0维系统中的Peierls和Jahn-Teller扭曲，2维系统中的电荷密度波现象），因此将探索结构转变与磁转变同时发生的可能性，从而产生巨磁热材料的一阶磁转变特征。镧系元素在各种各样的技术中发挥着重要作用，其中许多，也许是大多数，依赖于它们的f电子在化学中所起的独特作用。它们的光学性质在含镧激光材料中起着至关重要的作用。在磁性材料中，镧系元素是硬永磁体功能的核心。在这个项目中，我们将研究含有镧系元素的分子是否可能起到分子磁铁的作用——最小的可想象的“条形磁铁”。如果是这样的话，含有镧系元素的分子可以帮助提供纳米技术的信息存储容量，这将远远超过目前的硬盘技术。同样感兴趣的是含镧材料，其磁性，结构性质和热性质是耦合的。这种材料有望用于新一代磁性冰箱，其效率将超过当前的制冷技术。培养学生、本科生和研究生以及博士后，使他们在这些领域的工业和学术职位上有竞争力，仍然是一个优先事项。