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

无线电频率干扰是民用和军用通信网络中的一项关键挑战，物联网中快速增长的互联设备数量加剧了这一挑战。该项目将通过开发基于高灵敏度的电可调谐磁性微波探测器(即自旋二极管)阵列的自旋电子频谱分析仪来应对这一挑战，以实现对高功率射频信号的快速和可编程的频率分析和过滤。该电路结合了现有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，因为检测频率及其对应的阈值电平可以电子地重新配置。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。研究成果将被整合到一门新开发的课程中，该课程由西北大学PI教授，重点是磁性和自旋电子学。所提出的频谱分析仪和限幅器的智能优点来自于一种具有非常高的检测灵敏度和电可调特性的新型自旋电子器件结构。由于界面自旋-轨道相互作用，磁传感层表现出很大的电压控制的磁各向异性，这提高了它对射频信号的敏感性。该装置将由产生磁化自动振荡的直流电流偏置，其频率由电流值确定。然后，由于将自动振荡锁定到输入射频信号，实现了大的整流电压。因此，二极管的检测频率可以通过电流来调谐。该项目将开发自旋二极管探测器阵列，每个自旋二极管探测器电调到特定频率，以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。其结果是一种紧凑、电可调和快速的频率选择限制器，它克服了现有解决方案的局限性。建议的设备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制造设备和工艺，并可从主要铸造厂获得。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.