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

对于电信、雷达和量子计算技术来说，能够在微波频率范围内产生信号的设备目前至关重要。迫切需要紧凑和高性能的器件，能够很容易地与其他经典或量子电路结合。该提案提出，通过应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装置的可能性。拟议的研究如果成功，不仅将促进科学领域的进步，而且还将产生教育影响，开发课程单元，通过吸引各级学生，特别是来自社会经济弱势群体的学生，学习应用物理和电子工程，提高学生对量子科学的理解。外展活动包括激发公众对磁性设备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，这是实现片上微波源、探测器和神经形态计算设备的一种很有前途的技术。现有的自旋力矩振荡器存在输出功率低、线宽宽以及需要复杂的外部支撑电路等问题，这极大地限制了其实际应用。为了克服这些困难，本项目设想了一种通过在微波谐振腔中放置自旋扭矩振荡器来实现大面积铁磁薄膜中的相干磁自振荡的新方法。磁体和微波谐振器之间的相互作用将导致它们的振荡动力学之间的耦合，从而进一步导致很大面积的磁性自由层中的宏观位相相干。通过制造建议的器件结构和测试微波输入输出关系，建议的器件结构不仅将产生一种新型的相干、高功率、片上微波源，而且将丰富人们对自旋动力学和磁铁与微波之间的耦合物理的理解。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。

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.