We locally probe the magnetic fields generated by a spin-torque oscillator (STO) in a microbar of ferrimagnetic insulator yttrium-iron-garnet using the spin of a single nitrogen-vacancy (NV) center in diamond. The combined spectral resolution and sensitivity of the NV sensor allows us to resolve multiple spin-wave modes and characterize their damping. When damping is decreased sufficiently via spin injection, the modes auto-oscillate, as indicated by a strongly reduced linewidth, a diverging magnetic power spectral density, and synchronization of the STO frequency to an external microwave source. These results open the way for quantitative, nanoscale mapping of the microwave signals generated by STOs, as well as harnessing STOs as local probes of mesoscopic spin systems.

中文翻译：

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单轴传感器探测的绝缘子中的自旋扭矩振荡

我们使用金刚石中的单个氮空位（NV）中心的自旋来局部探测由自旋扭矩振荡器（STO）在亚铁磁绝缘体钇铁石榴石微棒中产生的磁场。NV传感器的组合光谱分辨率和灵敏度使我们能够解析多种自旋波模式并表征其阻尼。当通过自旋注入使阻尼充分降低时，这些模式将自动振荡，如线宽大大减小，磁功率谱密度发散以及STO频率与外部微波源的同步所示。这些结果为STO产生的微波信号的定量，纳米级测绘以及将STO用作介观自旋系统的局部探针开辟了道路。