Development of a Ferrimagnetic Terahertz Oscillator

太赫兹（THz）波段的电磁频谱是一个很大程度上未开发的资源，在成像、光谱学、传感、计算和通信方面具有潜在的应用。该项目旨在通过开发一种在室温下工作的新型紧凑高功率源来填补太赫兹技术的空白，并将太赫兹波段开放给目前受笨重和/或低温太赫兹源限制的应用。该项目将在科学与工程交叉领域培养2名研究生和至少2名本科生。社区大学生和少数族裔大学生将被纳入暑期研究项目。研究结果将纳入材料科学与工程系的课程，包括免费向公众开放的在线课程。pi将在剑桥科学节期间组织纳米天文台，向公众解释光刻和显微镜，并将通过Dow-MIT ACCESS多样性计划提供纳米技术的讲座和活动。提出的工作目标是通过利用由相邻重金属中的电流驱动的铁磁体的动态振荡行为来设计新型太赫兹（THz）源。太赫兹波段的电磁波谱是一个很大程度上未开发的资源，在成像、光谱、传感、计算和通信方面具有潜在的应用。阻碍广泛应用的是缺乏有效的、可调谐的宽带太赫兹源，以及在小尺寸设备中实现它们的方法。提出的研究将展示一种革命性的频率可调固态太赫兹发射器，其数字优点是目前最先进的技术所无法比拟的。将使所提出的太赫兹源成为可能的关键创新是在铁磁体中驱动到其角动量补偿点附近的太赫兹进动的大未补偿净磁化的偶极子辐射。在低阻尼氧化铁磁体中，可以实现频率超过1太赫兹的自旋霍尔电流驱动的相干自振荡，其中反铁磁交换相互作用可以实现超快动力学。基础研究将为高速反铁磁类自旋动力学和自旋电荷相互转换提供新的见解，以及设计多轴磁各向异性景观以定制动态磁化轨迹的新方法。可调谐自旋电子太赫兹发生器将作为概念验证紧凑太赫兹源。该项目将培养两名研究生和两名本科生。研究结果将纳入材料科学与工程系的课程。公众宣传将包括在剑桥科学节期间的纳米天文台，以及通过Dow-MIT ACCESS多样性计划举办的纳米技术讲座和活动。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The terahertz (THz) band of the electromagnetic spectrum is a largely untapped resource, with potential applications in imaging, spectroscopy, sensing, computing, and communications. This project aims to fill a gap in THz technology by developing a novel compact high-power source that operates at room temperature, and opening up the THz band to applications that are currently limited by the bulky and/or low temperature THz sources available today. The project will train 2 graduate students and at least 2 undergraduate students in an interdisciplinary area of science and engineering. Community college students and underrepresented minority college students will be included in summer research programs. Results from the research will be incorporated into coursework in the Materials Science and Engineering department, including online subjects that are available to the public free. The PIs will organize The NanoObservatory during the Cambridge Science Festival which explains lithography and microscopy to the general public, and will offer lectures and activities in nanotechnology through the Dow-MIT ACCESS diversity program.The objective of the proposed work is to engineer novel terahertz (THz) sources by harnessing the dynamical oscillatory behavior of a ferrimagnet driven by an electric current in an adjacent heavy metal. The THz band of the electromagnetic spectrum is a largely untapped resource, with potential applications in imaging, spectroscopy, sensing, computing, and communications. Standing in the way of widespread applications is a lack of efficient, tunable broadband THz sources, and a means of implementing them in small form factor devices. The proposed research will demonstrate a revolutionary frequency-tunable solid-state THz emitter with figures of merit that are unmatched by the current state of the art. The key innovation that will enable the proposed THz source is the dipole radiation of a large uncompensated net magnetization in a ferrimagnet driven into THz precession near its angular momentum compensation point. Spin-Hall current-driven coherent auto-oscillations with frequency exceeding 1 THz will be achieved in low-damping oxide ferrimagnets in which antiferromagnetic exchange interactions enable ultrafast dynamics. The fundamental research will yield new insights into high-speed antiferromagnetic-like spin dynamics and spin-charge interconversion as well as new approaches to engineer multi-axis magnetic anisotropy landscapes to tailor dynamical magnetization trajectories. The tunable spintronic THz generators will serve as proof-of-concept compact THz sources. The project will train two graduate and two undergraduate students. Results from the research will be incorporated into coursework in the Materials Science and Engineering department. Public outreach will include The NanoObservatory during the Cambridge Science Festival and lectures and activities in nanotechnology through the Dow-MIT ACCESS diversity program.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.