Understanding Spin Diffusion Lengths in Metals and Oxides

了解金属和氧化物中的自旋扩散长度

基本信息

批准号：
1807124
负责人：
Christopher Leighton
金额：
$ 40.66万
依托单位：
University of Minnesota-Twin Cities
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-01 至 2021-11-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1807124&HistoricalAwards=false
关键词：
Understanding Spin Diffusion Lengths Metals

项目摘要

Non-technical abstract:High performance magnetic devices are ubiquitous in our society, the magnetic hard disk drives that power cloud data storage serving as one example. Underpinning technological advancement in this area is the ongoing progress in fundamental understanding of magnetism and magnetic materials. In this project, a fundamental problem relevant to "spin electronics" is being tackled, specifically how electron spins relax after being pumped from magnetic to non-magnetic materials. This is a poorly understood issue in magnetism, despite many scientific efforts and high importance for next generation devices. In this work, a particular type of nanomagnetic device is being used to understand, quantitatively, and for the first time, how specific materials defects control the relaxation of spins. In addition to advancing basic scientific knowledge, broader impact is being achieved through societal benefits from device applications, through education of students, and through outreach to the public. The latter involves collaboration with the Science Museum of Minnesota, developing exhibits and performances on the science of materials in our everyday lives, thus raising awareness of the role of materials research in our society.Technical abstract:Central to many spintronic phenomena and devices is the flow of a pure spin current, or a spin-polarized charge current, in a non-magnetic metal. A fundamental question in such a situation is over what distance does a non-equilibrium spin population relax in a non-magnetic metal, or: what is the spin diffusion length? Remarkably, while the basic mechanism governing metallic spin relaxation, the Elliot-Yafet mechanism, is known, there remain massive gaps in our understanding of this process. The individual effects of specific defects remain unknown, preventing quantitative or predictive understanding of spin transport. Addressing this problem, with its obvious technological relevance, would constitute a transformative advance. The essence of this project is to use non-local lateral spin valves to determine spin diffusion lengths in a variety of conventional and oxide-based metals. Elemental metals such as Al are being studied to separately quantify spin relaxation due to phonons, impurities, grain boundaries, surfaces, and interfaces, thus determining Elliott-Yafet constants for each defect. Metallic perovskite oxides are also being studied. These materials offer tremendous potential for spintronics, although an understanding of their spin diffusion lengths remains elusive. A progression from conventional metal-based devices to perovskite metals is being followed in this research, providing the first understanding of spin diffusion lengths in oxide ferromagnets and non-magnetic metals, a critical step in the development of oxide spintronics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要：高性能磁性设备在我们的社会中无处不在，为云数据存储提供动力的磁性硬盘驱动器就是一个例子。该领域技术进步的基础是对磁性和磁性材料的基本理解的不断进步。在这个项目中，正在解决与“自旋电子学”相关的一个基本问题，特别是电子自旋在从磁性材料泵浦到非磁性材料后如何弛豫。尽管有许多科学努力并且对下一代设备非常重要，但这是磁性中一个鲜为人知的问题。在这项工作中，一种特殊类型的纳米磁性装置首次被用来定量地理解特定材料缺陷如何控制自旋弛豫。除了推进基础科学知识之外，还通过设备应用带来的社会效益、学生教育和公众宣传来实现更广泛的影响。后者涉及与明尼苏达州科学博物馆的合作，开发有关我们日常生活中材料科学的展览和表演，从而提高人们对材料研究在我们社会中的作用的认识。技术摘要：许多自旋电子现象和设备的核心是非磁性金属中的纯自旋电流或自旋极化充电电流的流动。在这种情况下的一个基本问题是非磁性金属中非平衡自旋布居弛豫的距离是多少，或者：自旋扩散长度是多少？值得注意的是，虽然控制金属自旋弛豫的基本机制——埃利奥特-亚菲特机制——是已知的，但我们对这一过程的理解仍然存在巨大差距。特定缺陷的个体影响仍然未知，这阻碍了对自旋输运的定量或预测性理解。解决这个问题及其明显的技术相关性将构成一项变革性的进步。该项目的本质是使用非局部横向自旋阀来确定各种传统金属和氧化物基金属中的自旋扩散长度。人们正在研究铝等元素金属，以分别量化声子、杂质、晶界、表面和界面引起的自旋弛豫，从而确定每个缺陷的埃利奥特-亚菲特常数。金属钙钛矿氧化物也正在研究中。这些材料为自旋电子学提供了巨大的潜力，尽管对其自旋扩散长度的了解仍然难以捉摸。这项研究遵循从传统金属基器件到钙钛矿金属的进展，首次了解氧化物铁磁体和非磁性金属中的自旋扩散长度，这是氧化物自旋电子学发展的关键一步。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。