自旋-轨道 (自旋)转矩纳米振荡器的材料制备优化、微纳加工及其高频特性研究与应用探索

This project will study the steady magnetization dynamics of ferromagnets in novel spintronic functional material systems under the spin-orbital torque or spin torque by means of Anomalous Hall effect or spin polarized current in magnetic tunnel junctions or spin valves. In more details, the spin-orbital or spin torque modulates magnetization dynamics under various current (voltage), magnetic field or temperature will be focused on, and its physical mechanism will be studied systematically. Firstly, novel spintronic functional material systems (like magnetic nanometer-thick multilayer structure) will be designed, optimized and grown. Then, spin-orbital or spin torque nano-oscillators will be fabricated with the help of the micro- or nano- fabrication process. Finally, the oscillation frequency, output power, and linewidth, and their current/field/temperature/angle dependences of spin-orbital or spin torque nano-oscillators will be investigated. In the next step, we will design and optimize novel spin-orbital or spin torque nano-oscillators to improve their microwave performance through the phase locking technique or other methods, to achieve at least one of the key technologies of nano-oscillators with completely independent intellectual property rights, and to contribute to the basic research and application of nano-oscillators in China.

本项目拟利用自旋-轨道转矩效应和自旋转矩效应研究自旋电子学新型功能材料体系中铁磁材料的等幅稳态进动，即研究纳米振荡器在电流(电压)、磁场、温度等作用下，自旋-轨道或自旋转矩调控磁矩进动的物理机理。首先设计和优化自旋电子学新型功能材料体系(如磁性纳米多层膜结构)，通过微纳加工工艺制备自旋-轨道(自旋)转矩纳米振荡器，研究纳米振荡器高频工作频率、输出功率、半高宽等微波性质，并利用锁相技术设计和优化具有应用价值的自旋-轨道(自旋)转矩纳米振荡器，实现至少一种具有完全自主知识产权的纳米振荡器关键技术，为国内纳米振荡器的基础研究和应用探索做出贡献。

项目组研究了几种自旋电子学新型功能材料体系（纳米环状磁性隧道结等）在电流、磁场、温度等作用下自旋-轨道或自旋转矩调控磁矩进动等物性性质。获得了纳米环形MgO势垒磁性隧道结及其阵列的磁组态及磁矩动力学翻转相图，详细测量了铁磁性自由层磁矩的进动区域；观察了在纳米环状隧道结中由于形状的限制效应而在某一固定磁场下激发的两种不同模式的铁磁共振并将现有的微波探测器灵敏度提升一倍; 发现了在纳米环状磁性隧道结中自旋转矩效应和热扰动共同促成的Backhopping现象并在此基础上提出了真随机数发生器原理型器件。通过该项目，在基于纳米环状隧道结的自旋纳米振荡器中实现了两种有知识产权的自旋纳米振荡器结构设计和原理型器件。在项目执行期间获得1项美国发明专利和5项中国发明专利授权，发表有项目致谢号的SCI收录论文共计有20篇，协助培养博士毕业生5名。