Materials World Network: Targeting New Complex Itinerant Magnets Using Experiment and Theory

材料世界网络：利用实验和理论瞄准新型复杂巡回磁体

• 批准号: 1209135
• 负责人: Gordon Miller
• 金额: $ 30万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1209135&HistoricalAwards=false
• 关键词: Materials; World; Network; Targeting; New

TECHNICAL SUMMARYThis Materials World Network project,supported by the Solid-State and Materials Chemistry program and the Office of Special Programs in the Division of Materials Research, combines synthesis, diffraction, magnetization measurements with first principles electronic structure theory to design and understand new intermetallic ferromagnets and antiferromagnets. Experimental activity will focus on complex 4d and 5d metal-boride frameworks with magnetic 3d elements, e.g., Cr-Ni, inserted in voids to create magnetic structures with low-dimensional character. The metal-boride framework is a structurally strong, electronically robust, and provides a mechanism for magnetic exchange between adjacent magnetic metal atoms via the spins on the conduction electrons. Previous support focused on structures with four-fold symmetry; new discoveries expand our studies to six-fold and three-fold symmetry, in which frustration effects can influence magnetic behavior. Specifically, atomic and magnetic structures will be determined by X-ray and neutron diffraction as well as magnetization experiments. Electronic structure theory will probe the energetics of various atomic and magnetic structures by evaluating orbital and exchange interactions to establish chemical rules and to calculate transition temperatures for ferromagnetic or antiferromagnetic behavior. Theoretical results will provide feedback for subsequent synthetic targets with predicted magnetic behavior. Theory will also investigate the magnetic structures and characteristics of the simpler MM'P and MM'As (M, M' = V-Cu), which also show tetragonal and trigonal symmetries. This work will establish the generality of the theoretical approach. At present, no general chemical rules exist to target compounds with permanent magnetic behaviour. The successful outcome will establish the evolution of magnetic behavior within a single structural family to identify trends in magnetic behavior as various chemical and physical parameters change in systematic ways. NON-TECHNICAL SUMMARYThis scientific effort combines experiment and theory to design and prepare new magnets belonging to a recently discovered family of metal-rich compounds. The complexity of these compounds allows chemical tuning, that can be accomplished by synthesis and can be studied by quantum chemistry. From this systematic study of a chemical family of compounds, a new set of rules will emerge for targeting metallic, permanent magnets, which have numerous technological applications. The real challenge will be to predict, via theory, the temperature range at which such targeted materials will show permanent magnetic behavior. The scientific effort will provide students a truly interdisciplinary problem, by combining chemistry and physics with experiment and theory. The student participants will clearly learn how different scientific subjects and approaches impact other scientific areas. The student participants from Aachen, Germany and Ames, Iowa will have opportunities for exchange, and they will learn both experimental and theoretical components of research in solid-state chemistry. In summary, this effort represents a strong, synergistic coupling of experiment and theory that will identify and characterize new magnetic materials, with the broader goal of establishing predictive rules for building newer magnets.

该材料世界网络项目由固态与材料化学项目和材料研究部特别项目办公室支持，将合成、衍射、磁化测量与第一性原理电子结构理论结合起来，设计和理解新的金属间铁磁体和反铁磁体。实验活动将集中在复杂的4d和5d金属硼化物框架与磁性3d元素，如Cr-Ni，插入到空隙中，以创建具有低维特征的磁性结构。金属-硼化物框架结构坚固，电子坚固，并通过导电电子上的自旋为相邻磁性金属原子之间的磁交换提供了机制。之前的支持主要集中在四重对称的结构上；新的发现将我们的研究扩展到六重对称和三重对称，其中挫折效应可以影响磁行为。具体来说，原子和磁性结构将通过x射线和中子衍射以及磁化实验来确定。电子结构理论将通过评估轨道和交换相互作用来探索各种原子和磁性结构的能量学，以建立化学规则并计算铁磁或反铁磁行为的转变温度。理论结果将为后续具有预测磁性的合成目标提供反馈。理论还将研究更简单的MM' p和MM' as （M， M' = V-Cu）的磁结构和特征，它们也显示出四方和三角对称性。这项工作将建立理论方法的通用性。目前，没有一般的化学规则存在的目标化合物具有永久磁性行为。成功的结果将在单一结构家族中建立磁性行为的演变，以确定各种化学和物理参数以系统的方式变化时磁性行为的趋势。这项科学努力结合实验和理论来设计和制备属于最近发现的富金属化合物家族的新磁铁。这些化合物的复杂性允许化学调谐，这可以通过合成来完成，也可以通过量子化学来研究。从对化合物化学家族的系统研究中，将出现一套新的规则，用于瞄准具有众多技术应用的金属永磁体。真正的挑战将是通过理论来预测这些目标材料表现出永久磁性行为的温度范围。通过将化学和物理与实验和理论相结合，科学努力将为学生提供一个真正的跨学科问题。学生参与者将清楚地了解不同的科学主题和方法如何影响其他科学领域。来自德国亚琛和爱荷华州艾姆斯的学生参与者将有机会进行交流，他们将学习固态化学研究的实验和理论组成部分。总之，这项工作代表了实验和理论的强大协同耦合，将识别和表征新的磁性材料，与建立预测规则的更广泛的目标建立新的磁铁。