A Spin Torque Oscillator Maser Device Enabled by Spin-Microwave Photon Coupling

能够在微波频率范围内产生信号的设备对于目前的电信、雷达和量子计算技术至关重要。我们迫切需要能够与其他经典电路或量子电路轻松结合的紧凑、高性能的器件。本提案提出利用微波信号与磁性材料相互作用产生的新机制，探索实现一种性能优于现有微波源器件的可能性。如果这项研究成功，不仅会促进科学领域的进步，而且还会通过开发课程模块来提高学生对量子科学的理解，吸引各个层次的学生，特别是来自社会经济弱势群体的学生，进入应用物理和电子工程的研究，从而产生教育影响。外展活动包括激发公众对磁性器件领域令人兴奋的机会的广泛认识。该项目采用的方法是基于自旋扭矩振荡器的现象，这是一种很有前途的技术，可以实现片上微波源、探测器和神经形态计算设备。现有的自旋力矩振荡器存在输出功率低、线宽宽、外部支撑电路复杂等问题，极大地限制了其实际应用。为了克服这些困难，本课题提出了一种在微波谐振腔中放置自旋转矩振荡器的方法来实现大面积铁磁薄膜的相干磁自振荡。磁体与微波谐振腔之间的相互作用将导致其振荡动力学之间的耦合，进而导致大面积磁自由层的宏观相相干性。通过对所提出的器件结构的制作和微波输入输出关系的测试，所提出的器件结构不仅将产生一种新颖的相干、高功率的片上微波源，而且还将丰富人们对自旋动力学和磁体与微波耦合物理的认识。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。

Devices that can generated signals in the microwave frequency range are vital for now a days for telecommunication, radar and quantum computing technologies. There is a critical need for compact and high-performance devices that can be easily combined with other classical or quantum circuit. This proposal proposes to explore the possibility of realizing a new microwave source device that will have superior performance over existing ones, by applying new mechanisms resulting from the interactions between microwave signal and magnetic materials. The proposed research, if successful, will not only lead to advancement in the scientific areas, but also have educational impact by developing course modules that will enhance students’ understanding on quantum science by attracting students at all levels, particularly from socio-economically disadvantaged groups, into the study of applied physics and electronic engineering. Outreach activities include inspiring broad public awareness in the exciting opportunities in magnetic device domains. The approach used in the project is based on the phenomenon of spin torque oscillator, which is one promising technique for realizing on-chip microwave sources, detectors, and neuromorphic computing devices. Existing spin torque oscillators suffer from challenges in low output power, broad linewidth as well as the requirement for complicated external supporting circuits, which greatly limits their practical applications. In this project, to overcome these difficulties, a new approach for realizing coherent magnetic self-oscillation in a large area ferromagnetic thin film by placing a spin torque oscillator into a microwave resonator is conceived. The mutual interactions between the magnet and microwave resonator will lead to a coupling between their oscillation dynamics, which will further result in macroscopic phase coherence in magnetic free layer with very large area. By fabricating the proposed device structures and testing on the microwave input-output relationship, the proposed device structure will not only result in a novel coherent, high power, on-chip microwave source, but also enrich people’s understanding on spin dynamics and the coupling physics between magnets and microwave.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.