Spintronic Spectrum Analyzer and Limiter based on Tunable Magnetic Tunnel Junction Arrays

射频干扰是民用和军用通信网络面临的关键挑战，物联网中互联设备数量的快速增长加剧了这一挑战。该项目将通过开发一种自旋电子频谱分析仪来解决这一挑战，该分析仪基于具有高灵敏度的电可调谐磁性微波探测器阵列（即自旋二极管），以实现快速和可编程的频率分析和高功率射频信号的滤波。所提出的电路结合了现有的基于硬件的频率选择限制器的速度和软件方法的可重构性，因为检测频率及其相应的阈值水平可以通过电重新配置。除了潜在的经济影响外，该项目还将通过纳入重要的外联和教育活动而产生更广泛的影响。研究成果将整合到西北大学PI教授的一门新开发的课程中，该课程侧重于磁学和自旋电子学。所提出的频谱分析仪和限幅器的智力优势来自于一种新颖的自旋电子器件结构，具有非常高的检测灵敏度和电可调谐特性。由于界面自旋轨道相互作用，磁传感层被设计成具有较大的电压控制磁各向异性，从而提高了其对射频信号的灵敏度。该装置将被直流电流偏置，产生磁化的自动振荡，其频率由电流值决定。一个大的整流电压，然后实现由于锁定的自振荡输入射频信号。因此，二极管的检测频率可以通过电流来调节。该项目将开发自旋二极管探测器阵列，每个探测器都被电调谐到一个特定的频率，对输入信号进行实时频谱分析。二极管的输出电压将与参考电压（其本身可以在现场重新配置）进行比较，从而检测超过功率限制的信号。结果是一个紧凑，电可调谐和快速频率选择限制器，克服了现有解决方案的局限性。所提出的器件可以单片集成到后端硅制造中，使用已经为磁存储器和传感器产品开发的批量生产设备和工艺，并且可以从主要代工厂获得。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。

Radio-frequency interference is a key challenge in civilian and military communication networks, and is exacerbated by the fast-growing number of interconnected devices in the Internet of Things. This project will address this challenge by developing a spintronic spectrum analyzer, based on arrays of electrically tunable magnetic microwave detectors (i.e., spin diodes) with high sensitivity, to achieve fast and programmable frequency analysis and filtering of high-power radio-frequency signals. The proposed circuit combines the speed of existing hardware-based frequency-selective limiters with the reconfigurability of software approaches, since detection frequencies and their corresponding threshold levels can be reconfigured electrically. In addition to its potential economic impact, this project will also achieve broader impact through the incorporation of significant outreach and education activities. Research results will be integrated into a newly developed course that is taught by the PI at Northwestern University, focusing on Magnetism and Spintronics.The intellectual merit of the proposed spectrum analyzer and limiter derives from a novel spintronic device structure with very high detection sensitivity and electrically tunable characteristics. The magnetic sensing layer is engineered to exhibit large voltage-controlled magnetic anisotropy due to interfacial spin-orbit interaction, which boosts its sensitivity to radio-frequency signals. The device will be biased by a direct electric current creating auto-oscillations of the magnetization, the frequency of which is determined by the current value. A large rectified voltage is then achieved due to locking of the auto-oscillations to the input radio-frequency signal. Thus, the detection frequency of the diode can be tuned by an electric current. This project will develop arrays of spin diode detectors, each electrically tuned to a particular frequency, to perform real-time spectral analysis of incoming signals. Output voltages of the diodes will be compared with a reference voltage (which itself can be reconfigured in the field), thereby detecting signals exceeding the power limit. The result is a compact, electrically tunable and fast frequency-selective limiter that overcomes the limitations of existing solutions. The proposed devices can be monolithically integrated into back-end-of-line silicon manufacturing, using volume manufacturing equipment and processes that have already been developed for magnetic memory and sensor products, and are available from major foundries.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.