CAREER: Spin-Torque Oscillator Arrays

本研究研究了多层巨磁电阻(GMR)和隧道磁阻(TMR)自旋扭矩振荡器(STO)阵列中静磁自旋波的产生、传播、相互作用和吸收。随着最近自旋-扭矩转移和自持振荡器的展示，一类新的振荡器已经出现，具有极高的可调谐性和出色的射频性能潜力。然而，最近的结果表明，由于单个设备中存储的能量很少，这些新设备的潜力受到单个设备的大相位噪声的限制。一种潜在的解决方案是对大阵列中的多个STO进行锁相。本研究致力于多器件阵列中STO-STO相互作用的基础科学研究，旨在为可控、可扩展的STO振荡器阵列奠定基础。具体地说，本研究计划集中于研究自旋波STO相互作用基础科学的三个任务：1)研究多层STO堆栈上的静磁表面波动力学，2)研究STO的静磁表面波激发发射，以及3)STO-STO相互作用的空间相关性和标度。智力优势：这项研究将发展关于多层GMR/TMR电堆中静磁自旋波传播的基础知识，如波数、衰变、方向性对各种参数的依赖关系，以及将自旋波能量传输到相邻STO的最佳可能的薄膜配置。此外，STO-波相互作用的研究还将加深对单个STO的自旋波发射效率、单个STO对自旋波的散射/吸收/放大、自旋波场中STO的频率拉动效应以及激发粒子与连续平面波的非线性相互作用的新认识。更广泛的影响：这项研究将开发STO阵列，具有低相位噪声振荡器和高可调谐性，适用于频谱灵活的射频系统。与这些研究计划相结合的是一项综合努力，旨在开发新的跨学科课程，重点放在设备物理及其应用的基础上，创建虚拟实验室，使全球的学生能够探索这些基本概念，并向当地社区的小学生和高中生介绍令人兴奋的磁学和电子领域。此外，一个综合的研究和教育计划将为当地社区和全球的学生提供直接途径，通过网络部署的虚拟实验室和教育教程来研究纳米设备的基本原理。教育工作的重点将是通过虚拟实验室为学生开发体验式学习活动，使学生能够通过实验和探索学习概念，补充传统的讲授式教育方法。

This research investigates magnetostatic spin-wave generation, propagation, interaction and absorption in multi-layer Giant magnetoresistance (GMR) and Tunnel magnetoresistance (TMR) spin-torque oscillator (STO) arrays. With the recent demonstration of spin-torque transfer and self-sustained oscillators, a new class of oscillator has emerged with extreme tunability and potential for excellent RF performance. Recent results have shown, however, that the potential of these new devices is limited by the large phase noise of individual devices due to the small amount of energy stored in a single device. A potential solution is the phase-locking of many STOs in a large array. This research focuses on the fundamental science of STO-STO interaction in multi-device arrays with the goal of laying the foundation for controllable, scalable arrays of STO oscillators. Specifically, this research proposal focuses on three tasks investigating fundamental science of spin-wave STO interaction: 1) Study of magnetostatic surface wave dynamics on multi-layer STO stacks, 2) Study of magnetostatic surface wave stimulated emission by an STO, and 3) Spatial dependence and scaling of STO-STO interactions. Intellectual merit: This research will develop fundamental knowledge about magnetostatic spin wave propagation in multi-layer GMR/TMR stacks such as dependence of wavenumber, decay, directionality on various parameters and also the best possible film configuration for transferring spin wave energy to adjacent STOs. In addition the proposed study on STO-wave interaction will develop new understanding about spin wave emission efficiency of a single STO, spin wave scattering/absorption/amplification by a single STO, frequency pulling effect of a STO under spin wave field as well as non-linear interaction of an excited particle (STO) with a continuous plane wave. Broader impacts: This research will develop STO arrays, with low phase noise oscillators and high tunability for spectrum-agile RF systems. Combined with these research programs is an integrated effort for the development of new interdisciplinary courses that focus on the fundamentals of device physics and their applications, the creation of virtual laboratories that enable students around the globe to explore these fundamental concepts, and the introduction of elementary and high school students in local communities to the exciting field of magnetics and electronics. Furthermore, an integrated research and educational program will provide direct access for students, in local communities and around the globe, to investigate fundamentals of nanoscale devices through web-deployed virtual laboratories and educational tutorials. The educational efforts will focus on developing experiential learning activities for students via virtual labs to enable students to learn concepts through experimentation and exploration, complimenting traditional lecture based educational methods.