Current - Induced Torques in Ferromagnetic and Antiferromagnetic Structures

铁磁和反铁磁结构中的电流感应扭矩

• 批准号: 1010768
• 负责人: Daniel Ralph
• 金额: $ 60万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1010768&HistoricalAwards=false
• 关键词: Current; Induced; Torques; Ferromagnetic; Antiferromagnetic

****NON-TECHNICAL ABSTRACT****Electrons, which are the fundamental particle responsible for electrical currents within metals, possess not only electrical charge but also carry an intrinsic spin. In most existing electrical devices, the spin does not play any role. However, in the past decade new generations of technology have begun development in which the electron spins are manipulated to add new functionalities. This type of spin-electronics, or "spintronics", has already achieved widespread use in the form of magnetic-field sensors in hard disk drives, and it is also under intense development to make computer memories in which spin-aligned electrical currents reorient ferromagnetic components to store information. The goal of this research project is to develop new understanding about the interactions between spin-aligned electrons and a ferromagnet or other selected materials, and particularly to understand current-induced torques that can arise from these interactions. The project will include the development of new experimental techniques to achieve accurate measurements of the strength and direction of current-induced spin torques, and to image how the magnetization of a ferromagnet moves in response to the torque. This work will advance basic understanding of electron spin dynamics and will provide information and techniques that will be needed for the development of magnetic memories and other technologies. The graduate and undergraduate students supported by the project will also gain an excellent interdisciplinary training in nanoscience.****TECHNICAL ABSTRACT****The aim of this project is to develop new understanding about spin-transfer torques, which are mechanisms by which spin-polarized electrical currents can transfer their spin angular momentum to ferromagnets and (perhaps) antiferromagnets to reorient their magnetic moments. Already it has been shown that spin transfer can provide much stronger torques per unit current compared to using conventional magnetic fields, and spin torques can efficiently drive magnetic switching and precession. The proposed work will invent new experimental techniques to enable quantitative measurements of the strength and direction of spin torques in ferromagnetic layers. It will advance the technology of ultrafast electrical measurements and time-resolved x-ray microscopy to understand the magnetic dynamics that can be excited by spin torques. The project will also extend the study of spin torques to new classes of materials, specifically magnetic nanoparticles and antiferromagnets, for which interesting effects are predicted but no definitive experiments have been performed. The impact of project will be to advance basic understanding of electron spin dynamics and to provide information and experimental techniques that will be needed for the development of spin-torque-driven magnetic memories, frequency-tunable nanoscale microwave sources, and other technologies. The graduate and undergraduate students supported by the project will also gain an excellent interdisciplinary training in nanoscience.

* 非技术性摘要 * 电子是金属中产生电流的基本粒子，它不仅具有电荷，还具有固有的自旋。 在大多数现有的电子器件中，自旋不起任何作用。然而，在过去的十年中，新一代的技术已经开始发展，其中电子自旋被操纵以增加新的功能。 这种类型的自旋电子学，或“自旋电子学”，已经以硬盘驱动器中的磁场传感器的形式获得了广泛的应用，并且它也在加紧开发，以制造计算机存储器，其中自旋对准的电流重新定向铁磁组件以存储信息。 该研究项目的目标是对自旋对准电子与铁磁体或其他选定材料之间的相互作用产生新的理解，特别是理解这些相互作用可能产生的电流感应扭矩。 该项目将包括开发新的实验技术，以准确测量电流感应自旋扭矩的强度和方向，并对铁磁体的磁化如何响应扭矩而移动进行成像。 这项工作将推进对电子自旋动力学的基本理解，并将提供磁存储器和其他技术发展所需的信息和技术。 该项目支持的研究生和本科生也将获得纳米科学的优秀跨学科培训。技术摘要 * 本项目的目的是发展对自旋转移力矩的新理解，自旋转移力矩是自旋极化电流将其自旋角动量转移到铁磁体和（可能）反铁磁体以重新定向其磁矩的机制。 已经表明，与使用常规磁场相比，自旋转移可以提供每单位电流强得多的扭矩，并且自旋扭矩可以有效地驱动磁切换和进动。 拟议的工作将发明新的实验技术，使定量测量的强度和方向的自旋扭矩在铁磁层。 它将推进超快电测量和时间分辨x射线显微镜技术，以了解自旋扭矩可以激发的磁动力学。 该项目还将把自旋力矩的研究扩展到新的材料类别，特别是磁性纳米粒子和反铁磁体，预测了这些材料的有趣效应，但还没有进行确定的实验。该项目的影响将是推进对电子自旋动力学的基本理解，并为自旋扭矩驱动的磁存储器，频率可调纳米微波源和其他技术的发展提供所需的信息和实验技术。 该项目支持的研究生和本科生也将获得纳米科学的优秀跨学科培训。