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Spin Transport in Metals and Oxides

金属和氧化物中的自旋输运

基本信息

批准号：
1507048
负责人：
Christopher Leighton
金额：
$ 38.03万
依托单位：
University of Minnesota-Twin Cities
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2015
资助国家：
美国
起止时间：
2015-08-15 至 2018-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1507048&HistoricalAwards=false
关键词：
Spin Transport Metals Oxides

项目摘要

Non-technical description:Magnetism in thin layers or films of materials, and at interfaces between multiple layers, has attracted attention for many years. This is due to basic scientific interest, but also technological importance, as magnetic films enable such devices as the hard disk drives that now power cloud storage. Despite the maturity of such "spintronic" technologies there remain surprising gaps in the understanding of such materials, as well as major obstacles to next generation devices. One example is the manner in which magnetism can be induced in otherwise non-magnetic metals by injecting electrons across an interface with a magnetic metal. This is termed "spin injection", the subsequent motion of the electrons enabling "spin transport". Despite the fact that working technologies rely upon these effects, many fundamental questions remain unanswered, including what limits how far injected spin currents can persist. The goal of this project is to understand exactly this, focusing on the all-important role of imperfections in the materials. In addition to elucidating the poorly understood basic physics, this also contributes to the development of next generation hard drive read heads. This project does this not only with conventional magnetic metals, but also in the new realm of conductive oxide materials. In addition to impact in both science and technology, these activities train undergraduate and graduate students in an active, interdisciplinary research field, directly contributing to a skilled US workforce. Outreach to the public is also achieved, primarily through an educational program developed by the principal investigator that can impact up to 500 school students a year.Technical description:This project uses the separation of charge and spin currents enabled by the nanoscopic lateral non-local spin valve to dramatically improve the understanding of spin injection and relaxation in metals and oxides. The goal is to develop a general physical understanding of the factors that limit spin diffusion lengths and lifetimes in non-magnetic metals and oxides, thus directly contributing to the exploration of low resistance-area product sensor technologies for next generation hard disk drive read heads. The factors inducing spin relaxation in non-magnetic metals are being systematically deconvoluted in this work, providing a full understanding of the role of magnetic impurities, spin-orbit scattering centers, grain boundaries, surfaces, interfaces, and phonons. The research additionally includes novel experiments aimed at understanding the role of local magnetic moments, Kondo physics, and even magnetic interactions and fluctuations on spin transport in metals with magnetic impurities. The work will gradually move from conventional metals to conductive oxides, exploring the opportunities provided by highly spin polarized complex oxide spin injectors, the prospects to understand the fundamentals of spin injection, diffusion and relaxation in oxide metals, and the potential for fascinating new physics combining spin transport with electronic phase transitions.

非技术性描述：材料薄层或薄膜中以及多层之间界面处的磁性多年来一直受到关注。这是由于基本的科学兴趣，也是技术的重要性，因为磁性薄膜使硬盘驱动器等设备成为云存储的动力。尽管此类“自旋电子”技术已经成熟，但对此类材料的理解仍然存在令人惊讶的差距，并且下一代设备仍面临重大障碍。一个例子是通过在与磁性金属的界面上注入电子，可以在其他非磁性金属中感生磁性的方式。这被称为“自旋注入”，电子的后续运动使“自旋输运”成为可能。尽管工作技术依赖于这些效应，但许多基本问题仍然没有答案，包括什么限制了注入的自旋电流可以持续多久。这个项目的目标是准确地理解这一点，重点是材料中缺陷的重要作用。除了阐明人们所知甚少的基本物理学之外，这也有助于下一代硬盘驱动器读取磁头的开发。该项目不仅涉及传统的磁性金属，而且涉及导电氧化物材料的新领域。除了在科学和技术的影响，这些活动培养本科生和研究生在一个活跃的，跨学科的研究领域，直接有助于熟练的美国劳动力。此外，主要通过首席研究员开发的教育计划，每年可影响多达500名学生。技术说明：该项目利用纳米级横向非局域自旋阀实现的电荷和自旋流分离，极大地提高了对金属和氧化物中自旋注入和弛豫的理解。其目标是发展一个一般的物理理解的因素，限制自旋扩散长度和非磁性金属和氧化物的寿命，从而直接有助于下一代硬盘驱动器读头的低电阻面积产品传感器技术的探索。在非磁性金属中诱导自旋弛豫的因素在这项工作中被系统地解卷积，提供了对磁性杂质，自旋轨道散射中心，晶界，表面，界面和声子的作用的充分理解。该研究还包括旨在了解局部磁矩，近藤物理学，甚至磁性相互作用和磁性杂质金属中自旋输运波动的作用的新实验。这项工作将逐渐从传统的金属转移到导电氧化物，探索高度自旋极化的复杂氧化物自旋注入器提供的机会，了解氧化物金属中自旋注入，扩散和弛豫的基本原理的前景，以及将自旋输运与电子相变相结合的迷人新物理学的潜力。