Spin Transport in Metals and Oxides

非技术描述：材料薄层或薄膜中的磁性，以及多层之间的界面，多年来一直引起人们的关注。这是由于基本的科学兴趣，但也是由于技术的重要性，因为磁性薄膜使诸如硬盘驱动器之类的设备能够为云存储提供动力。尽管这种“自旋电子”技术已经成熟，但对这种材料的理解仍然存在令人惊讶的差距，以及下一代设备的主要障碍。一个例子是，磁性可以在非磁性金属中通过注入电子穿过磁性金属的界面而产生。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，但许多基本问题仍未得到解答，包括是什么限制了注入的自旋电流能持续多久。这个项目的目标是准确地理解这一点，专注于材料中缺陷的所有重要作用。除了阐明人们对基本物理的理解不足之外，这也有助于下一代硬盘读头的开发。这个项目不仅用传统的磁性金属，而且在导电氧化物材料的新领域。除了对科学和技术产生影响外，这些活动还在一个活跃的跨学科研究领域培养本科生和研究生，直接为美国的熟练劳动力做出贡献。与公众的接触也得到了实现，主要是通过一个由首席研究员开发的教育项目，每年可以影响多达500名学生。技术描述：该项目利用纳米级横向非局部自旋阀实现电荷和自旋电流的分离，极大地提高了对金属和氧化物中自旋注入和弛缓的理解。目标是对限制非磁性金属和氧化物中自旋扩散长度和寿命的因素进行一般的物理理解，从而直接有助于探索下一代硬盘驱动器读头的低电阻面积产品传感器技术。在这项工作中，诱导非磁性金属中自旋弛豫的因素被系统地解卷积，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。这项研究还包括一些新颖的实验，旨在理解局部磁矩的作用，近藤物理，甚至是磁性杂质金属中自旋输运的磁相互作用和波动。这项工作将逐步从传统金属转移到导电氧化物，探索高自旋极化复合氧化物自旋注入器提供的机会，了解氧化金属中自旋注入、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结合起来的迷人新物理学的潜力。

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.