School of Electronic Science and Engineering, Nanjing University, 210093 Nanjing, China.
Department of Physics, University of Gothenburg, 412 96 Gothenburg, Sweden.
Nanoscale. 2017 Jan 19;9(3):1285-1291. doi: 10.1039/c6nr07903b.
Spin Hall nano-oscillators (SHNOs) are an emerging class of pure spin current driven microwave signal generators. Through the fabrication of 20 nm nano-constrictions in Pt/NiFe bilayers, we demonstrate that SHNOs can be scaled down to truly nanoscopic dimensions, with the added benefit of ultra-low operating currents and improved power conversion efficiency. The lateral confinement leads to a strong shape anisotropy field as well as an additional demagnetizing field whose reduction with increasing auto-oscillation amplitude can yield a positive current tunability contrary to the negative tunability commonly observed for localized excitations in extended magnetic layers. Micromagnetic simulations corroborate the experimental findings and suggest that the active magnetodynamic area resides up to 100 nm outside of the nano-constriction.
自旋霍尔纳米振荡器（SHNO）是一类新兴的纯自旋流驱动微波信号发生器。通过在 Pt/NiFe 双层膜中制备 20nm 纳米限制结构，我们证明了 SHNO 可以缩小到真正的纳米尺度，同时具有超低工作电流和提高的功率转换效率的优点。横向限制导致强形状各向异性场以及附加的退磁场，随着自激振荡幅度的增加，退磁场的减小可以产生正电流可调性，与在扩展磁层中局部激发通常观察到的负可调性相反。磁动力学模拟证实了实验结果，并表明活性磁动力学区域位于纳米限制之外可达 100nm。
