Current-Driven Magnetodynamics in Metallic Heterostructures

****技术摘要****本项目探索由电流驱动的金属异质结构中的高频磁动力学，既从基础物理学的角度出发，也从它们与磁电子学或自旋电子学技术重要领域的相关性出发。自旋电子学建立在一组互补的现象之上，其中磁组态影响输运性质，输运电流改变磁组态。后者的一个例子是所谓的自旋-传递-扭矩现象，它指的是一种利用电流操纵自旋的新方法。这种基于量子力学交换相互作用的方法提供了前所未有的自旋分布的时空控制，并吸引了大量的关注，因为它将有趣的基础科学与广泛的技术应用前景相结合。该项目将利用最近开发的磁微接触光谱学技术，该技术具有独特的能力，可以在尚未探索的长度和时间尺度上探测电流驱动的磁动力学。该技术的优点将用于研究铁磁体中的自旋传递扭矩，也用于寻找最近在理论基础上提出的反铁磁材料中的新型自旋传递效应。研究和教育活动的连贯整合将使博士生接触到自旋电子学，并为他们进行经济上可行和创新应用的研究和开发做好准备。****非技术摘要****降低功耗和提高逻辑和存储设备的速度是电子领域长期关注的问题。例如，在使用磁矩作为存储位的磁存储器中，快速可靠地感知（读取）和反转（写入）力矩并以最小的能量消耗是至关重要的。自旋-传递-转矩（STT）现象是一种通过电流控制和操纵磁矩的新方法，它可以提供这一点；在这里，电流在磁矩上产生STT转矩，并可用于在存储介质中写入（开关）磁位，例如在STT随机存取存储器（STTRAM）中，被吹捧为潜在的“通用”存储器，结合了其他存储器（如闪存，SRAM和DRAM）的许多吸引人的属性。具体来说，这种存储器的封装密度和速度应该得到改善。在这种情况下，提出的实验将是这种技术的速度和可扩展性限制的测试平台。该项目将探索由电流驱动的高频磁动力学，从基础科学的角度以及它们在高速高密度磁记录技术中的应用。研究和教育活动的连贯整合将使博士生能够进行经济上可行和创新应用的研究和开发。

****Technical Abstract****This project explores high-frequency magnetodynamics in metallic heterostructures driven by an electric current, both from the fundamental physics point of view as well as from their relevance to the technologically important area of magnetoelectronics, or spintronics. Spintronics is built on a complementary set of phenomena in which magnetic configurations influence transport properties and transport currents alter magnetic configurations. An example of the latter is the so-called spin-transfer-torque phenomenon which refers to a novel method to manipulate spins using an electrical current. This method, based on quantum mechanical exchange interaction, offers unprecedented spatial and temporal control of spin distributions and attracts a great deal of attention because it combines interesting fundamental science with the promise of applications in a broad range of technologies. This project will exploit the recently developed magnetic microcontact spectroscopy technique which is unique in its ability to probe the current-driven magnetodynamics on yet unexplored length and time scales. The advantages of the technique will be used to study spin-transfer-torque in ferromagnets and also to look for novel spin transfer effects in antiferromagnetic materials which have recently been proposed on theoretical grounds. Coherent integration of research and educational activities will expose PhD students to spintronics and prepare them to conduct research and development of economically feasible and innovative applications.****Non-Technical Abstract****Reducing power and increasing speed of logic and memory devices are of perennial interest in electronics. For instance, in magnetic memories, which make use of magnetic moments as the memory bits, it is pivotal to reliably sense (read) and reverse (write) the moments fast and with minimum energy dissipated. Spin-transfer-torque (STT) phenomenon, which refers to a novel method to control and manipulate magnetic moments by an electric current, can provide just that; here the current generates the STT torque on magnetic moments and can be used to write (switch) magnetic bits in storage media as, e.g. in STT Random Access Memory (STTRAM), being touted as a potential "universal" memory incorporating many of the attractive attributes of other memories like flash, SRAM and DRAM. Specifically, the packing density and speed of such a memory should be improved. In this context, the proposed experiments will be a test bed for the speed and scalability limits of such technology. This project will explore high-frequency magnetodynamics driven by an electric current both from the fundamental science point of view as well as from their relevance to applications in high-speed high-density magnetic recording technology. Coherent integration of research and educational activities will prepare PhD students to conduct research and development of economically feasible and innovative applications.