Active microwave nanodevices based on nonlocal spin injection

随着科学和工程界寻找能够克服当前电子在功率、速度和集成度方面的限制的新信息技术，人们正在探索利用电子电荷和自旋自由度的设备。 这项研究将研究一种称为非局域自旋阀的新型器件，在这种器件中，电荷流和自旋流被有效地分离。 所提出的器件结构从根本上优化了操作特性，能够有效地生成用于信息传输和处理的微波信号，同时最大限度地减少电流的负面影响。 拟议的研究将探索几何形状和操作特性之间的关系，以及将这些器件纳入集成信号生成，传输和操纵的纳米级电路的可能性。 一些本科生和研究生将接受使用先进技术制造和表征新型纳米器件的现代方法的培训，并获得自旋电子学和材料科学的基本和实用概念的知识。 将特别强调通过小学科学日、每年的亚特兰大科学节和物理学/天文学开放日以及为高中生提供研究经验，向公众进行宣传。（自旋电子学）的动机是在不需要电荷流的器件中降低能量耗散的潜力，但实际上自旋电子器件通常利用大电流，这导致显著的耗散，甚至损坏器件。 本研究计划将探讨及发展以非定域自旋注入磁性异质结构所产生的纯自旋电流驱动的奈米磁性微波振荡器。 结构的优化将使器件在适度的驱动电流下工作，同时最大限度地减少焦耳热和奥斯特场对光谱特性的影响。 在所提出的设备中的电荷和自旋流的分离提供了前所未有的几何形状的灵活性，这将被利用来优化光谱特性和效率，将设备纳入纳米级自旋波（磁振子）电路，并实现多个设备的同步操作。 该目标将通过额外关注纳米级动态磁化状态的基本特性来增强，以解决由自旋电流驱动的纳米磁性系统的自振荡机制。

As the scientific and engineering communities search for new information technologies capable of overcoming the current limitations of electronics in power, speed, and integration, devices exploiting both the electron's charge and spin degrees of freedom are being explored. The proposed research will investigate a new type of devices termed nonlocal spin valves, where the charge and spin flows are efficiently separated. The proposed device structure radically optimizes the operational characteristics, enabling efficient generation of microwave signals for information transmission and processing, while minimizing the negative effects of electrical current. The proposed research will explore the relationship between geometry and operational characteristics, and the possibility to incorporate these devices into nanoscale circuits that integrate signal generation, transmission, and manipulation. Several undergraduate and graduate students will be trained in the modern methods of fabrication and characterization of novel nanodevices using advanced techniques as well as gaining knowledge in fundamental and practical concepts of spintronics and materials science. Special emphasis will be placed on the outreach to the general public, through the Elementary School Science Day, annual Atlanta Science Festival, and Physics/Astronomy Open House, and by providing research experience for high school students.Development of spin-based electronics (spintronics) is motivated by the potential of reduced energy dissipation in devices that do not require charge flows, but in practice spintronic devices usually utilize large electrical currents that result in significant dissipation and even damage to devices. This research project will explore and develop nanoscale magnetic microwave oscillators driven by pure spin current produced by nonlocal spin injection in a magnetic heterostructure. Optimization of the structure will enable device operation at modest driving currents, while minimizing Joule heating and the effects of Oersted field on the spectral characteristics. The separation of the charge and the spin flows in the proposed device provides an unprecedented flexibility of the geometry, which will be exploited to optimize the spectral characteristics and efficiency, incorporate devices into nanoscale spin wave (magnonic) circuits, and achieve synchronized operation of multiple devices. The goal will be augmented by additional focus on the fundamental properties of the dynamical magnetization states at nanoscale, to address the mechanisms that enable auto-oscillation of nanomagnetic systems driven by spin currents.