Spin Coherence and Quantum Transport in Magnetic Nanostructures

本实验旨在了解人工量子结构中相干电子自旋动力学和自旋相关输运的基本方面。这些研究为未来几代磁电子器件中相干自旋输运的开发奠定了基础。实验重点是由II-VI磁性半导体（MS）制成的模型纳米结构，允许人们系统地定制限制电子态和低维局域矩分布之间的自旋相互作用。该项目由高度互动的努力组成，结合了复杂的质谱纳米结构（数字磁异质结构，磁性二维电子气体（2DEGs）和量子自旋点）的并发开发，以及具有高时间（~100 fs）和空间（~100 nm）分辨率（飞秒法拉第旋转和时间分辨近场扫描光学显微镜）和低温磁输运的最先进的自旋动力学探针。近几十年来，复杂的固态制造技术的发展使人造原子结构（“纳米结构”）的构建成为可能，其中一个或多个维度达到纳米级（人类头发直径的十亿分之一）。同时，光学测量技术的发展也使得人们能够以前所未有的高速度（超快光谱学）和高空间清晰度（近场显微镜）记录物理现象。在这个高度互动的项目中，我们采用最先进的制造和测量技术的强大组合来研究新型“磁性纳米结构”中电子的动态运动，其中磁性原子嵌入在工程半导体中。这些基础研究为未来几代磁电子器件奠定了基础，这些器件将利用电子和磁原子之间的量子力学相互作用，用于高速通信器件和超高密度存储器。＊＊＊

9701072 Awschalom This experimental effort is aimed at understanding fundamental aspects of coherent electronic spin dynamics and spin-related transport in artificial quantum structures. Such investigations form the basis for the exploitation of coherent spin transport in future generations of magneto-electronic devices. The experiments focus on model nanostructures fabricated from II-VI magnetic semiconductors (MS), allowing one to systematically tailor spin interactions between confined electronic states and low dimensional distributions of local moments. The project is comprised of highly interactive efforts that combine the concurrent development of sophisticated MS nanostructures (digital magnetic heterostructures, magnetic two-dimensional electron gases (2DEGs), and quantum spin dots) with state-of-the- art spin dynamical probes having high temporal (~100 fs) and spatial (~100 nm) resolution (femtosecond Faraday rotation and time-resolved near-field scanning optical microscopy) and low- temperature magnetotransport. %%% Recent decades have witnessed the development of sophisticated solid state fabrication techniques that enable the construction of artificial atomic architectures ("nanostructures") in which one or more dimensions are at the nanoscale (a billionth the diameter of a human hair). There has also been a concurrent development of optical measurement techniques that allow one to record physical phenomena at unprecedently high speeds (ultrafast spectroscopy) and with very high spatial definition (near field microscopy). In this highly interactive project, we employ a powerful combination of state-of-the-art fabrication and measurement techniques to study the dynamic motion of electrons in new classes of "magnetic nanostructures," wherein magnetic atoms are embedded within an engineered semiconductor. These fundamental investigations lay the groundwork for future generations of magneto-electronic devices that would exploit the quantum mecha nical interactions between electrons and magnetic atoms for high-speed communication devices and ultra-high density memories. ***