Collaborative Research: Large-Amplitude, Easy-Plane Spin-Orbit Torque Oscillators

合作研究：大振幅、简易平面自旋轨道扭矩振荡器

• 批准号: 2236160
• 负责人: Satoru Emori
• 金额: $ 31.15万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2236160&HistoricalAwards=false
• 关键词: Collaborative; Research; Large; Amplitude; Easy

The rapid growth of information and communications technology continues to have an outsized impact on global energy consumption. It is therefore crucial to create new, energy-efficient electronic components that benefit this technology. One such essential device converts a constant voltage input into an oscillating voltage output. The goal of this research is to develop a new class of microscale electronic oscillators, called easy-plane spin-orbit torque oscillators, which are compatible with standard industrial fabrication techniques. By exploiting novel device geometries and recently-discovered phenomenon in ferromagnetic materials, easy-plane spin-orbit torque oscillators could address many problems plaguing conventional oscillators, such as small output signal, nanoscale confinement, and thermal instability. Applications for these new oscillators range from microwave communications to brain-inspired computing. This project also has an outreach component designed to teach K-12 students, especially those from schools underserved in science, how to build simple magnetic motors from household items, with the goal of sparking interest in science at an early age.This research aims to produce foundational knowledge for new spin-orbit torque oscillators based on current-in-plane spin valves, in which the free-layer magnetization precesses at a large cone angle of nearly 90 degrees. The research is inspired by a recent discovery that an electric current in an in-plane magnetized film produces an out-of-plane spin current. This novel spin current can then generate an antidamping torque, driving large-angle precession in the free layer of the spin valve. The first thrust of the research will identify the mechanisms of the out-of-plane spin current and the resulting antidamping torque in spin valves. To this end, first-principles calculations and spin-torque ferromagnetic resonance experiments will be performed on spin valves with systematically varied compositions and structures. The second thrust of the research will determine the critical requirements for stable, large-angle precession in spin valves through micromagnetic simulations and electrical device characterization. A successful outcome will lead to easy-plane oscillators with more than an order of magnitude higher signal and stability compared to existing spin-orbit torque oscillators, owing to a larger swing in magnetoresistance and stronger immunity against thermal fluctuations. Furthermore, the research will produce crucial fundamental knowledge on unconventional spin currents and spin torques, which can control a variety of magnetization dynamics (e.g., perpendicular magnetic switching, superfluid-like exchange flow) in next-generation spintronic devices.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.

信息和通信技术的快速发展继续对全球能源消耗产生巨大影响。因此，创造有利于这项技术的新型节能电子元件至关重要。一种这样的重要设备将恒定电压输入转换为振荡电压输出。这项研究的目标是开发一种新型微型电子振荡器，称为简易平面自旋轨道扭矩振荡器，它与标准工业制造技术兼容。通过利用新颖的器件几何形状和最近发现的铁磁材料现象，易平面自旋轨道扭矩振荡器可以解决困扰传统振荡器的许多问题，例如输出信号小、纳米级限制和热不稳定性。这些新型振荡器的应用范围从微波通信到类脑计算。该项目还有一个外展部分，旨在教授 K-12 学生，特别是那些来自科学服务不足的学校的学生，如何用家居用品建造简单的磁电机，目的是激发人们对科学的兴趣。这项研究旨在为基于电流面内自旋阀的新型自旋轨道扭矩振荡器提供基础知识，其中自由层磁化以近 90 度的大锥角进动。这项研究的灵感来自于最近的一项发现，即面内磁化薄膜中的电流会产生面外自旋电流。这种新颖的自旋电流可以产生抗阻尼扭矩，驱动自旋阀自由层中的大角度进动。该研究的第一个重点将确定自旋阀中面外自旋电流的机制以及由此产生的抗阻尼扭矩。为此，将在具有系统变化的成分和结构的自旋阀上进行第一原理计算和自旋扭矩铁磁共振实验。该研究的第二个重点将通过微磁模拟和电气器件表征来确定自旋阀稳定、大角度进动的关键要求。与现有的自旋轨道扭矩振荡器相比，成功的结果将导致简单平面振荡器的信号和稳定性高出一个数量级以上，因为磁阻摆幅更大，并且对热波动的免疫力更强。此外，该研究还将产生关于非常规自旋电流和自旋扭矩的重要基础知识，这些知识可以控制下一代自旋电子器件中的各种磁化动力学（例如，垂直磁开关、类超流体交换流）。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查进行评估，被认为值得支持 标准。