Spin Transport Far From Equilibrium

自旋输运远离平衡

• 批准号: 1104951
• 负责人: Paul Crowell
• 金额: $ 37万
• 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: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1104951&HistoricalAwards=false
• 关键词: Spin; Transport; Far; Equilibrium

Technical abstractThis project will advance the understanding of charge and spin transport in semiconductors under conditions that are very far from equilibrium. The research addresses new devices in which spin currents in semiconductors are generated and detected using ferromagnetic metals. The experiments will address how fundamental phenomena such as the spin-orbit interaction, hyperfine interactions, hot electron populations, and dimensionality impact spin-polarized transport. First, a set of experiments will be carried out to elucidate the connection between the spin Hall effect in semiconductors, which has only recently been observed in transport measurements, and its inverse effect, in which a spin-polarized current generates a charge current. A second set of experiments will probe spin-polarized carriers far from equilibrium, where departures from ordinary linear response have recently been observed. The potential for using these non-linear effects to control spin currents will be demonstrated. Third, the manifestation of spin-orbit coupling in traditional transport effects, including weak-anti-localization, will be correlated with direct measurements of the spin transport and dynamics using techniques developed in the PI's group. Finally, the proposed research will address some of the critical steps required to undertake similar experiments in reduced dimensions. These experiments address some of the critical steps required to implement devices, such as a spin transistor, which will require a deeper understanding of ferromagnet-semiconductor heterostructures.Non-technical abstract Magnetism is ubiquitous in modern technology. Mass data storage, as in computer hard drives, depends on the magnetism of metals, such as iron, cobalt or nickel. Semiconductors, while also a critical component of modern technologies, are not magnetic. This project focuses on a materials system that is made out of thin layers of a ferromagnetic material (iron) and a semiconductor. The ultimate goal of this line of research is the achievement of new classes of devices that carry out both the processing and storage of information on a single chip. This project focuses on fundamental properties that determine how electron spins (the carriers of magnetic information) can be injected, controlled, and detected inside a semiconductor. The research will include experiments probing the new and unusual conditions present when spins in semiconductors are generated near surfaces, in very large numbers, or in very thin layers. These physical phenomena lie at the heart of new proposals for magneto-electronic devices that could be enabled by this research.

技术摘要该项目将增进对远离平衡条件下半导体中电荷和自旋输运的理解。 该研究涉及使用铁磁金属产生和检测半导体中自旋电流的新设备。这些实验将解决自旋轨道相互作用、超精细相互作用、热电子布居和维度等基本现象如何影响自旋极化输运。 首先，将进行一组实验来阐明半导体中的自旋霍尔效应（最近才在传输测量中观察到）与其反效应（其中自旋极化电流产生充电电流）之间的联系。 第二组实验将探测远离平衡的自旋极化载流子，最近观察到与普通线性响应的偏离。 将展示使用这些非线性效应来控制自旋电流的潜力。 第三，传统输运效应中自旋轨道耦合的表现，包括弱反局域化，将与使用 PI 小组开发的技术对自旋输运和动力学的直接测量相关。 最后，拟议的研究将解决在缩小尺寸下进行类似实验所需的一些关键步骤。 这些实验解决了实现自旋晶体管等器件所需的一些关键步骤，这需要对铁磁体-半导体异质结构有更深入的了解。非技术抽象磁性在现代技术中无处不在。 海量数据存储（如计算机硬盘驱动器）取决于铁、钴或镍等金属的磁性。 半导体虽然也是现代技术的关键组成部分，但没有磁性。 该项目重点研究由铁磁材料（铁）和半导体薄层制成的材料系统。 这一系列研究的最终目标是实现在单个芯片上进行信息处理和存储的新型设备。该项目重点研究决定电子自旋（磁信息载体）如何在半导体内部注入、控制和检测的基本特性。 该研究将包括实验，探索当半导体中的自旋在表面附近、大量或在非常薄的层中产生时出现的新的和不寻常的条件。 这些物理现象是这项研究可以实现的磁电子设备新建议的核心。