Collaborative Research: Collective and Coherent Spin Organization in Magnetic Semiconductor Nanostructures

这个实验项目探索了从二维电子气体到零维量子点的低维系统中电子、局部矩和核自旋的集体和相干自旋行为。实验的重点是由II-VI磁性半导体制成的模型纳米结构，该模型可以系统地定制以调节限制电子态，磁性离子和原子核之间的自旋相互作用。该项目结合了复杂纳米结构和最先进的自旋探针的开发，具有高时间（~100 fs）和空间（~100 nm）分辨率，以及高磁矩灵敏度（~105玻尔磁子）。微加工悬臂梁将用于寻找磁性半导体纳米结构中的集体自旋效应。这些纳米结构中的动态自旋组织将使用“全光”磁共振技术进行研究，包括电子的自旋进动、局部矩和核自旋。耦合时间分辨输运的相干光谱学将探测介观系统（线）中的动态自旋输运，其中核极化是利用光泵浦系统地变化的。最后，将发展近场扫描光学共振技术，以实现二维电子自旋系统的空间分辨磁共振成像。从这个项目中获得的纳米结构中集体自旋响应的知识对于未来几代磁电子器件中自旋过程的相干控制可能是重要的。固态物理、材料科学和先进仪器的高级技术培训将为学生在学术和工业环境中的职业生涯做好准备。这个实验凝聚态物理项目探索了从“电子片”（2D电子气体）到“电子盒”（0D量子点）等低维系统中电子、磁性原子和原子核的复杂量子力学行为。实验使用由一系列材料（II-VI磁性半导体）制成的模型纳米结构，其中被称为“自旋”的量子力学特性可以系统地改变。对纳米结构中自旋输运的基本理解可能会使基于固态量子力学相互作用的新技术成为可能。该项目由合作努力组成，将复杂的纳米结构与具有高时间（~100飞秒）和空间（~100纳米）分辨率和高自旋灵敏度（~ 105个磁性原子）的最先进的自旋探针相结合。实验范围从超灵敏磁强计，到“全光学”自旋共振显微镜，到电子自旋输运的动力学研究。虽然主要关注的是基础物理，但所获得的知识对于在未来几代高速磁电子器件中发展自旋过程相干控制的概念非常重要，其潜在应用范围从超快切换到量子计算。该研究涉及材料物理和先进仪器的先进技术培训，为学生在学术和工业环境中做出直接贡献做好准备。

This experimental project explores collective and coherent spin behavior of electrons, local moments and nuclear spins in low dimensional systems ranging from 2D electron gases to 0D quantum dots. The experiments focus on model nanostructures fabricated from II-VI magnetic semiconductors which can be systematically tailored to modulate spin interactions between confined electronic states, magnetic ions and nuclei. The project combines development of sophisticated nanostructures and state-of-the-art spin probes having high temporal (~100 fs) and spatial (~100 nm) resolution, and high magnetic moment sensitivity (~105 Bohr magnetons). Microfabricated cantilevers will be used to search for collective spin effects in magnetic semiconductor nanostructures. Dynamical spin organization in these nanostructures will be studied using an "all-optical" magnetic resonance technique, encompassing spin precession of electrons, local moments and nuclear spins. Coherent optical spectroscopy coupled with time-resolved transport will probe dynamical spin transport in mesoscopic systems (wires) wherein the nuclear polarization is systematically varied using optical pumping. Finally, near field scanning optical resonance techniques will be developed to achieve spatially resolved magnetic resonance imaging of 2D electron spin systems. Knowledge of the collective spin response in nanostructures gained from this project may be important for coherent control of spin processes in future generations of magneto-electronic devices. Advanced technical training in solid state physics, materials science, and advanced instrumentation will prepare students for careers in academic and industrial environments.%%% This experimental condensed matter physics project explores the complex quantum mechanical behavior of electrons, magnetic atoms and nuclei in low dimensional systems ranging from "electron sheets" (2D electron gases) to "electron boxes" (0D quantum dots). The experiments use model nanostructures fabricated from a family of materials (II-VI magnetic semiconductors) in which the quantum mechanical property known as "spin" can be systematically varied. A fundamental understanding of spin transport in nanostructures may enable new technologies based on quantum mechanical interactions in the solid state. The project is comprised of a collaborative effort that combines development of sophisticated nanostructures with state-of-the-art spin probes having high temporal (~100 femtoseconds) and spatial (~100 nanometer) resolution, and high spin sensitivity (~ 105 magnetic atoms). Experiments range from ultrasensitive magnetometry, to "all-optical" spin resonance microscopy, to dynamical studies of electron spin transport. While the principal focus is on fundamental physics, knowledge gained will be important for developing concepts in the coherent control of spin processes in future generations of high speed magneto-electronic devices, with potential applications ranging from ultrafast switching to quantum computation. This research involves advanced technical training in materials physics and advanced instrumentation, and prepares students to make immediate contributions both in academic and industrial environments.