Current-driven magnetic sources at microwave frequency

微波频率源是从移动设备到通信再到计算等各种应用的关键技术组件。需要开发非常紧凑的源，并且开发灵活的源，这意味着它们的频率可以在尽可能短的时间尺度上改变。一个很好的候选者是纳米级磁性振荡器，它通过直流应用产生高度可调的微波频率。电流。这些磁振荡器的输出功率不足，线宽太宽，难以在技术上应用，但如果能将它们连接起来，使它们的微波输出同步，则功率和线宽问题都可以克服。虽然以前已经将几个磁振荡器耦合在一起，但设计它们以使它们以可扩展的方式同步一直是困难的。此外，了解振荡器之间的纳米尺度磁相互作用是一个有趣的科学问题，具有超越技术的影响。该项目将在跨学科的环境中培养本科生和研究生，并将为科学教师提供研究经验。在这项提案中，研究团队引入了三个创新概念，以克服可伸缩同步纳米级磁性振荡器的挑战。首先，他们建议使用新兴的磁振子领域的概念来设计、建模和制造周期阵列中由自旋霍尔效应驱动的横向磁振荡器。其次，他们将使用时空磁显微镜对这些结构的动力学模式进行实验研究，这将有助于揭示真实设备中单个STO是如何与其邻居耦合的。这是最近横向自旋霍尔振荡器设备的突破提供的一个新机会，因为磁性振荡器网络以前是基于直接注入、垂直传输设备的。在这些设备中，磁性层被埋藏起来，很难成像。映像的可用性为基于特定的设备级洞察来设计设备创造了机会。第三个创新概念是利用频闪成像从磁模式研究损耗机制。传统上，频闪方法对非相干过程是盲目的，比如自旋波模之间的耦合可以导致动态增强的磁阻尼。通过将与频闪镜相称和不相称的微波驱动场结合在一起，研究小组将研究如何在有用的磁模和虚假的磁模之间传递能量。这项研究的洞察力将使新的和更好的设计能够使磁振荡器同步。

Microwave frequency sources are a critical component of technology for applications ranging from mobile devices to communications to computing. There is a need to develop extremely compact sources, and to develop sources that are agile, meaning their frequency can be shifted on the shortest possible timescale. A good candidate is nanoscale magnetic oscillators that produce highly tunable microwave frequencies through the application of d.c. current. Singly, these magnetic oscillators have insufficient output power and too broad a linewidth to be applied in technology, however, if they can be connected to each other so that they synchronize their microwave output, both the power and the linewidth problem can be overcome. While a few magnetic oscillators have been coupled together previously, it has been difficult to design them so that they synchronize in a scalable way. Additionally, understanding the nanoscale magnetic interactions between oscillators is an interesting scientific problem that has implications beyond technology. This project will train both undergraduate and graduate students in an interdisciplinary environment, and it will offer research experience for science teachers.In this proposal, the research team introduces three innovate concepts to overcome the challenge of scalably synchronizing nanoscale magnetic oscillators. First, they propose to design, model and fabricate lateral magnetic oscillators driven by the spin Hall effect in a periodic array using concepts from the emerging field of magnonics. Second, they will employ spatiotemporal magnetic microscopy to experimentally examine the dynamical modes of these structures, which will help reveal how individual STOs are coupled to its neighbors in real devices. This is a new opportunity offered by recent breakthroughs in lateral spin Hall oscillator devices because magnetic oscillator networks were previously based on direct injection, vertical transport devices. In those devices, the magnetic layers are buried and very difficult to image. The availability of imaging creates an opportunity to engineer devices based on specific, device-level insight. The third innovate concept is to use stroboscopic imaging to study loss mechanisms from magnetic modes. Traditionally, stroboscopic methods are blind to incoherent processes, like the coupling between spin wave modes that can lead to dynamically enhanced magnetic damping. By combining microwave driving fields that are both commensurate and incommensurate with the stroboscope, the research team will examine how energy can be transferred between useful magnetic modes and spurious magnetic modes. The insights from this research will enable new and better designs to synchronize magnetic oscillators.