Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States.
ACS Nano. 2012 Jul 24;6(7):6115-21. doi: 10.1021/nn301222v. Epub 2012 Jun 11.
The excitation of the steady-state precessions of magnetization opens a new way for nanoscale microwave oscillators by exploiting the transfer of spin angular momentum from a spin-polarized current to a ferromagnet, referred to as spin-transfer nano-oscillators (STNOs). For STNOs to be practical, however, their relatively low output power and their relatively large line width must be improved. Here we demonstrate that microwave signals with maximum measured power of 0.28 μW and simultaneously narrow line width of 25 MHz can be generated from CoFeB-MgO-based magnetic tunnel junctions having an in-plane magnetized reference layer and a free layer with strong perpendicular anisotropy. Moreover, the generation efficiency is substantially higher than previously reported STNOs. The results will be of importance for the design of nanoscale alternatives to traditional silicon oscillators used in radio frequency integrated circuits.
通过利用自旋极化电流向铁磁体转移自旋角动量，即自旋转移纳米振荡器（STNO），稳态进动磁化的激发为纳米级微波振荡器开辟了一条新途径。然而，为了使 STNO 实用化，必须提高其相对较低的输出功率和相对较宽的线宽。在此，我们证明了可以从具有面内磁化参考层和具有强垂直各向异性的自由层的 CoFeB-MgO 基磁隧道结中产生最大测量功率为 0.28 μW 且同时线宽窄至 25 MHz 的微波信号。此外，产生效率比以前报道的 STNO 要高得多。这些结果对于设计用于射频集成电路中的传统硅振荡器的纳米级替代方案非常重要。
