权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

First-Principles Studies of Spin-Orbit Torque and Magnetoresistance in Magnetic Nanostructures

磁性纳米结构中自旋轨道扭矩和磁阻的第一性原理研究

基本信息

批准号：
1916275
负责人：
Kirill Belashchenko
金额：
$ 36.38万
依托单位：
University of Nebraska-Lincoln
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-02-01 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1916275&HistoricalAwards=false
关键词：
First Principles Studies Spin Orbit

项目摘要

NONTECHNICAL SUMMARYThis award supports computational research and education aimed to advance understanding of the microscopic mechanisms responsible for the operation of nanoscale magnetic devices. The focus is on devices where electric currents cause dynamic reorientation of the magnetic moments. The PI will investigate devices made of two layers. One is a ferromagnet for which smallest microscopic magnets are aligned or an antiferromagnet for which the direction of the smallest microscopic magnets alternates along particular directions in the layer. The other layer is a normal metal that contains heavy atoms. The ultimate source of current-induced dynamics is spin-orbit coupling – an effect that arises in Einstein's theory of special relativity in which electrons which themselves act like tiny spinning tops interact with their own motion. The spin-orbit effect is strongest in materials comprised of heavy elements. These bilayer nanostructures are promising for applications in nanoelectronic devices, such as new types of magnetic memories, tunable high-frequency nano-oscillators, logic gates, and other building blocks for digital information processing and storage technologies. Improved understanding of the underlying mechanisms by which nanoscale magnetic devices can operate may enable the design of new nanoscale devices and help enhance the functionality and efficiency of existing prototypes. This research will be carried out using state-of-the-art computational tools. Graduate students will contribute to all aspects of the research and its dissemination; in so doing, they will receive extensive training in advanced condensed matter and materials theory, and modeling techniques. This project includes additional education activities involving the redesign of core graduate-level courses in physics based on modern active-learning and peer-instruction approaches.TECHNICAL SUMMARYThis award supports computational research and education on nonequilibrium spin torques produced by spin-orbit coupling in the presence of an in-plane electric current in heterostructures consisting of a ferromagnetic or antiferromagnetic layer and a normal-metal layer. This study will utilize first-principles calculations and a nonequilibrium Green’s function technique with direct supercell averaging over disorder configurations. The overall goal is to develop better understanding of coupled charge and spin transport in magnetic nanostructures and mechanisms contributing to spin-orbit torques and related magnetoresistive effects. This goal will be achieved by investigating the dependence of the damping-like, field-like, and higher-order angular components of spin-orbit torque on various materials and device parameters, including layer thicknesses, disorder type and strength, crystallographic orientation of the interface, surface oxidation, and the presence of capping or spacer layers. Comparison of the results with experimental data will help identify the underlying mechanisms and phenomenological theories that capture the key features and trends in the observations. Spin relaxation at metallic interfaces in heterostructures with current flowing perpendicular to the interfaces will also be studied using direct averaging over disorder configurations in multilayers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术性总结该奖项支持计算研究和教育，旨在促进对负责纳米磁性器件操作的微观机制的理解。重点是电流导致磁矩动态重新定向的设备。PI将研究由两层制成的器械。一种是铁磁体，其最小的微观磁体是对齐的，或者是反铁磁体，其最小的微观磁体的方向沿着层中的特定方向交替。另一层是含有重原子的普通金属。电流诱导动力学的最终来源是自旋-轨道耦合--这是爱因斯坦狭义相对论中出现的一种效应，在这种效应中，电子本身就像微小的旋转陀螺，与它们自己的运动相互作用。自旋轨道效应在由重元素组成的材料中最强。这些双层纳米结构在纳米电子器件中有应用前景，例如新型磁存储器，可调谐高频纳米振荡器，逻辑门以及用于数字信息处理和存储技术的其他构建模块。对纳米级磁性器件可以操作的基本机制的更好理解可以使新的纳米级器件的设计成为可能，并有助于增强现有原型的功能和效率。这项研究将使用最先进的计算工具进行。研究生将为研究及其传播的各个方面做出贡献;在这样做的过程中，他们将接受先进凝聚态和材料理论以及建模技术的广泛培训。该项目包括额外的教育活动，涉及重新设计的核心研究生水平的课程在物理学的基础上，现代主动学习和同侪教学approaches.Technical summaryThis奖支持计算研究和教育的非平衡自旋力矩产生的自旋轨道耦合在存在的平面电流的异质结构组成的铁磁或反铁磁层和正常的金属层。这项研究将利用第一性原理计算和非平衡绿色函数技术与直接超胞平均超过无序配置。总体目标是更好地理解磁性纳米结构中的耦合电荷和自旋输运以及有助于自旋轨道扭矩和相关磁阻效应的机制。这一目标将通过研究自旋轨道扭矩的类阻尼、类场和高阶角分量对各种材料和器件参数的依赖性来实现，包括层厚度、无序类型和强度、界面的晶体取向、表面氧化以及帽层或间隔层的存在。结果与实验数据的比较将有助于确定潜在的机制和现象学理论，这些理论捕捉了观察中的关键特征和趋势。在异质结金属界面的自旋弛豫与电流垂直流动的界面也将使用直接平均在多层disorder configurations的研究。这个奖项反映了NSF的法定使命，并已被认为是值得的支持，通过评估使用基金会的智力价值和更广泛的影响审查标准。