Spin Transport and Dynamics in Ferromagnet-Semiconductor Structures

技术这个项目将解决铁磁-半导体混合异质结中自旋输运和动力学的基本物理问题。我们将制作通过自旋注入产生大量非平衡自旋布居的器件，并研究自旋极化梯度对电荷和自旋输运的影响。将通过开发新的自旋敏感电子探测技术来探索自旋输运的机制。特别令人感兴趣的是自旋轨道效应和超精细效应，它们既提供了控制电子自旋的新手段，也提供了潜在的自旋弛豫来源。该项目由三个部分组成。首先，将开发新的设备，允许在亚微米长度尺度上产生偏振梯度。其次，对自旋动力学敏感的电学测量将被用来研究在金属-绝缘体转变附近的自旋和电荷输运的耦合。最后，半导体中自旋和铁磁体之间的动态耦合将在纳秒时间尺度上进行研究。非技术性磁性材料，如铁、钴或镍，是数据存储技术的基石，也是传感器的关键部件，从汽车到心脏除颤器等广泛应用。这个项目将探索一类新系统的基础科学，在这种系统中，铁等磁性材料与半导体相结合。研究生和本科生将接受纳米制造和测量技术方面的培训，以制造和研究基于这些材料的设备。最近的研究表明，电子可以从铁磁性金属转移到半导体中，同时以其自旋的形式保留磁信息，这类似于连接到电子上的小磁铁。该项目将确定磁性信息如何在半导体内部传输，然后以电子方式读出。将开发结合超小型磁铁和薄层半导体的新型电子设备。将讨论极小(小于1微米)和快速(小于十亿分之一秒)设备开发的新领域。这项研究的结果将在需要在单个电路元件中结合存储和处理能力的应用中有用。

TechnicalThis project will address the fundamental physics of spin transport and dynamics in hybrid ferrromagnet-semiconductor heterostructures. Devices in which large non-equilibrium spin populations are generated by spin injection will be fabricated, and the effects of spin polarization gradients on both charge and spin transport will be investigated. Mechanisms for spin transport will be probed by exploiting new spin-sensitive electrical detection techniques. Of particular interest are spin-orbit and hyperfine effects, which provide both new means for controlling electron spins as well as potential sources of spin relaxation. The project consists of three components. First, new devices will be developed allowing for the generation of polarization gradients on sub-micron length scales. Second, electrical measurements sensitive to spin dynamics will be used to investigate the coupling of spin and charge transport near the metal-insulator transition in GaAs and InxGa1-xAs. Finally, dynamic coupling between spins in the semiconductor and the ferromagnet will be investigated on nanosecond time scales.Non-technicalMagnetic materials such as iron, cobalt or nickel represent a cornerstone of data storage technologies, and they are also a critical component in sensors for a wide range of applications from cars to cardiac defibrillators. This project will explore the fundamental science of a new class of systems in which magnetic materials such as iron are combined with semiconductors. Graduate and undergraduate students will be trained in the nanofabrication and measurement techniques required to fabricate and study devices based on these materials. Recent research has shown that electrons can be transferred from ferromagnetic metals into semiconductors while preserving magnetic information in the form of their spin, which is analogous to a small magnet attached to the electron. This project will determine how magnetic information can be transported inside semiconductors and then read out electronically. New electronic devices combining very small magnets with thin layers of semiconductor will be developed. New frontiers in the development of extremely small (less than one micron) and fast (less than one billionth of a second) devices will be addressed. The output of this research will be useful in applications where storage and processing capabilities need to be combined in a single circuit element.