Novel Spintronic Microwave Devices

这项提议旨在开发一系列新型的自旋电子微波器件。这些器件是基于自旋电子器件(如磁隧道结)中的自由铁磁电极在微波存在下的磁化过程导致电阻变化的原理。检测微波功率的灵敏度和动态范围可与当前的射频二极管相媲美。MTJ传感器与射频二极管的不同之处在于，它们能够测量微波频率和相位，而无需使用传统的混频器进行外差检测。这大大简化了微波电路，并为小型化提供了机会。人们建议将自旋电子微波器件用于网络分析仪、频谱分析仪和微波近场成像等应用。这项拟议的研究的目的是演示和理解这些提议的自旋电子微波器件。重要的器件问题，如灵敏度、动态范围和空间分辨率将被解决，并与磁阻比、偏置电压、铁磁共振和衰减相关。一项旨在增加我们研究生就业机会的教育倡议也被纳入这项研究。智能的优点包括在自旋电子器件中引入自旋动力学，以实现更多的功能，特别是在微波频率下。该装置的原理基于与自旋扭矩转移、自旋泵浦和自旋二极管效应引入的现象根本不同的现象，但其简单可能立即影响并显著促进当前的微波技术。几种新颖的设计是基于这样的事实：(A)MTJ器件是导致整流效应的本征非线性，(2)MTJ器件响应于微波磁场，从而导致干扰效应，用于相位检测和信号增强，以及(3)微波电场和磁场都可以用于创建无源器件。广泛的影响包括可预见的和极有可能立即对当前的微波技术产生影响，特别是在网络分析仪、频谱分析仪和其他系统芯片(SoC)的产品中。这是可能的，因为自旋电子微波器件很小，不需要额外的电路，如混频器和移相器。这些特点也使固态微波近场成像成为可能。除了传统的教育和辅导外，我们还将启动一个教育和推广项目，以拓宽我们的学生的职业机会，并开发一门亟需的磁性信息存储和微波磁学课程。这两个主题对于保持美利坚合众国在当前全球经济中的竞争优势至关重要。

This proposal aims to develop an array of novel spintronic microwave devices. These devices are based on the principle that the magnetization of the free ferromagnetic electrode in spintronic devices such as magnetic tunnel junctions (MTJs) will precess in the presence of microwave, leading to a resistance change. The sensitivity and dynamic range for detecting microwave power is comparable to current RF diodes. What distinguishes MTJ sensors from RF diodes is that their capabilities to measure the microwave frequency and phase without using conventional mixers for heterodyne detection. This greatly simplifies microwave circuitry and offer opportunities for miniaturization. It is proposed to use spintronic microwave devices in applications like network analyzers, frequency spectrum analyzers, and microwave near field imaging. The objective of this proposed research is to demonstrate and understand these proposed spintronic microwave devices. The important device issues such as sensitivity, dynamic range, and spatial resolution will be addressed and related with magnetoresistance ratio, bias voltage, ferromagnetic resonance, and damping. An education initiative, targeting at enhancing career opportunity for our graduate students, is also integrated into this research. The intellectual merit includes introducing the spin dynamics in spintronic devices to achieve more functionalities, particularly at microwave frequencies. The device principles are based on the phenomena that are fundamentally different from those introduced from spin torque transfer, spin pumping, and spin diode effect, yet with simplicity that may immediately impact and significantly advance the current microwave techniques. Several novel designs are based on the facts that (a) a MTJ device is an intrinsically nonlinear which lead to a rectifying effect, (2) a MTJ device responds to microwave magnetic field which leads to interference effect for phase detection and signal enhancement, and (3) both microwave electric and magnetic fields can be used to create passive devices. The broad impacts include foreseeable and highly likelihood for immediate impacts on the current microwave technology, particularly in products of network analyzer, frequency spectrum analyzer, and other system on a chip (SoC). This is possible because spintronic microwave devices are small and does not need additional circuitry such as mixers and phase shifter. These features also make solid-state microwave near field imaging possible. Besides the traditional education and mentoring, we will initiate an education and outreach project in order to broaden career opportunities for our students and to develop a much needed course of magnetic information storage and microwave magnetics. Both subjects are critical to maintain the competitive edge of the Unite States of America in current global economy.