New Magnetoresistant Oxides of Mixed 3d/4d/5d Transition Metals

混合 3d/4d/5d 过渡金属的新型磁阻氧化物

• 批准号: 0303458
• 负责人: I-Wei Chen
• 金额: $ 54万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0303458&HistoricalAwards=false
• 关键词: New; Magnetoresistant; Oxides; Mixed; 3d

The objective of this proposal is to investigate a new series of mixed oxides containing primarily 4d and 5d transition metal cations, with additional magnetic impurities from the 3d transition-metal series. Our recent work on Fe3+-doped SrRuO3, CaRuO3, and Sr2RuO4 has revealed a very large magnetoresistance that was not previously known to exist in any ruthenate. More broadly, these results suggest that large local moments can arise in conducting oxides, and such materials can be exploited to gain new functionality and new understanding of ceramics. Our strategy is to use strongly magnetic 3d impurities to polarize the narrow 4d/5d conduction bands of the host, so that large electronic and magnetic responses are induced. The magnetic states and the energies of the 3d impurities will be systematically varied, by distorting the crystal structure and changing the composition, to match with those of the conduction bands of the host 4d/5d metals. Cation ordering will also be used as a tool to direct the crossover from spin-frustrated, intragrain magnetoresistance behavior to ferrimagnetic, intergrain magnetoresistance behavior. Single crystals, epitaxial thin films and polycrystals will be compared to determine the role of the grain-boundary effect, while first-principles calculations of model, ordered mixed-metal oxides will be made to benchmark the electronic energy levels of disparate cation d-orbitals. Meanwhile, synchrotron radiation will be utilized to determine the structures and electronic states of these compounds. Our educational program will offer training to undergraduates and high school teachers to provide them with laboratory and research experience. Further outreach to industry will be made through collaborative, synergistic, and exploratory research with a start-up company.Ceramic magnets are typically insulators. This project will explore new magnetic ceramics that become better conductors under a magnetic field. These materials have not been studied in the past but are becoming interesting because of the prospect of spintronic devices. Compared to conventional electronic devices, spintronic devices process more information by detecting and transmitting not only the charge but also the spin of electrons.

该提案的目的是研究主要包含 4d 和 5d 过渡金属阳离子以及来自 3d 过渡金属系列的附加磁性杂质的新系列混合氧化物。我们最近对 Fe3+ 掺杂的 SrRuO3、CaRuO3 和 Sr2RuO4 的研究揭示了非常大的磁阻，这是以前不知道任何钌酸盐中存在的。更广泛地说，这些结果表明导电氧化物中可能会出现大的局部力矩，并且可以利用此类材料来获得陶瓷的新功能和新的理解。我们的策略是使用强磁性 3d 杂质来极化主体的窄 4d/5d 导带，从而引发大的电子和磁响应。通过扭曲晶体结构和改变成分，3d 杂质的磁态和能量将系统地变化，以与主体 4d/5d 金属的导带相匹配。阳离子排序也将被用作引导自旋受阻、晶粒内磁阻行为到亚铁磁、晶间磁阻行为的交叉的工具。将比较单晶、外延薄膜和多晶，以确定晶界效应的作用，同时对模型、有序混合金属氧化物进行第一性原理计算，以对不同阳离子 d 轨道的电子能级进行基准测试。同时，同步加速器辐射将用于确定这些化合物的结构和电子态。我们的教育计划将为本科生和高中教师提供培训，为他们提供实验室和研究经验。将通过与初创公司的协作、协同和探索性研究来进一步向行业推广。陶瓷磁体通常是绝缘体。该项目将探索新型磁性陶瓷，使其在磁场下成为更好的导体。这些材料过去没有被研究过，但由于自旋电子器件的前景而变得有趣。与传统电子器件相比，自旋电子器件不仅通过检测和传输电子的电荷，还通过检测和传输电子的自旋来处理更多信息。