Spin Transport Far From Equilibrium

技术摘要本项目将促进对远离平衡条件下半导体中电荷和自旋输运的理解。 这项研究涉及新的设备，其中半导体中的自旋电流使用铁磁金属产生和检测。这些实验将解决基本现象，如自旋轨道相互作用，超精细相互作用，热电子种群和维度如何影响自旋极化传输。 首先，将进行一组实验，以阐明半导体中的自旋霍尔效应（最近才在输运测量中观察到）与其逆效应（自旋极化电流产生电荷电流）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，最近观察到偏离普通线性响应的情况。 利用这些非线性效应来控制自旋电流的潜力将被证明。 第三，自旋-轨道耦合在传统输运效应中的表现，包括弱反局域化，将与使用PI小组开发的技术直接测量自旋输运和动力学相关。 最后，拟议的研究将解决在降低维度的情况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器件所需的一些关键步骤，例如自旋晶体管，这将需要对铁磁-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。 大容量数据存储，如计算机硬盘驱动器，取决于金属的磁性，如铁，钴或镍。 半导体虽然也是现代技术的重要组成部分，但它没有磁性。 该项目的重点是由铁磁材料（铁）和半导体薄层制成的材料系统。 这一研究领域的最终目标是实现在单个芯片上同时处理和存储信息的新型设备。该项目的重点是确定电子自旋（磁信息的载体）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所存在的新的和不寻常的条件的实验。 这些物理现象是磁电子器件新提案的核心，这些新提案可以通过这项研究实现。

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.