无需磁场的自旋转移力矩纳米振荡器的制备及微波性能研究

Spin transfer nano-oscillators (STNOs) based on spin transfer torque effect have attracted intense attention due to their potential applications in microwave source and wireless microwave communications because of their unique characteristic such as simple structure, nanoscale size, frequency agile, and easy integration. The main issue for STNO preparation and its practical applications is: in most experiments performed up to now the microwave emissions were only observed in applied magnetic field, moreover with low output power. In this project we propose a novel STNO with a structure of perpendicular magnetized free layer/spacer/in-plane fixed layer, and will study fabrication and microwave properties of the corresponding nanodevice, and understand its internal mechanism by micromagnetism simulation. The expected achievements may lay the physical and material basis for designing high power STNOs without the need for magnetic field source. We believe this project will make a useful exploration in developing new spintronic materials and devices.

基于自旋转移力矩效应的自旋纳米振荡器，具有结构简单、尺寸小、宽频可调和易集成等特点，在微波源、无线微波通讯等领域具有广阔的应用前景,备受国内外科研工作者的关注。目前，国际上在自旋纳米振荡器制备和实际应用上所遇"瓶颈"问题是：绝大部分现有研制器件需在外加磁场下才能观测到微波发射，且输出功率低。本项目提出一种垂直磁化自由层/隔离层/面内磁化固定层的新型结构，研究基于该结构的纳米器件制备及微波特性，并结合微磁学模拟等手段理解其物理内涵，为设计无需磁场、高输出功率的自旋纳米振荡器件奠定物理和材料基础。该项目的顺利实施可为开发新型自旋电子材料和器件做出有益的探索及开拓。

本项目提出和研究了一种垂直磁化自由层/隔离层/面内磁化固定层的新型结构的自旋微波振荡器，并利用磁控溅射生长薄膜和微纳米加工技术制备纳米器件，系统研究基于该结构的纳米器件的微波特性，结合微磁学模拟等手段理解其物理内涵。经过项目的执行，取得了以下成果：.1）实现了无需磁场作用下的微波输出，同时发现该种器件所需的驱动电流密度很低，约为1.2 ×10^5 A cm^-2。.2）观测到了自旋微波振荡器与外部信号的锁相现象，并发现锁相技术能显著提高器件的微波性能。.3）设计出一种基于自旋微波振荡器的微波探测器，其探测灵敏度高达75,400 mV/mW，是目前商用微波探测器探测极限的20倍。.4）设计并制备出一种基于自由层面内磁化、固定层垂直磁化的新型复合磁化结构的自旋微波振荡器。.本项目的执行为设计无需磁场、高输出功率的自旋纳米振荡器件奠定物理和材料基础，对开发新型自旋电子材料和器件具有重要的基础研究意义和实用价值。