Fulara Himanshu, Zahedinejad Mohammad, Khymyn Roman, Dvornik Mykola, Fukami Shunsuke, Kanai Shun, Ohno Hideo, Åkerman Johan
Physics Department, University of Gothenburg, 412 96, Gothenburg, Sweden.
NanOsc AB, Electrum 229, 164 40, Kista, Sweden.
Nat Commun. 2020 Aug 11;11(1):4006. doi: 10.1038/s41467-020-17833-x.
Spin Hall nano-oscillators (SHNOs) are emerging spintronic devices for microwave signal generation and oscillator-based neuromorphic computing combining nano-scale footprint, fast and ultra-wide microwave frequency tunability, CMOS compatibility, and strong non-linear properties providing robust large-scale mutual synchronization in chains and two-dimensional arrays. While SHNOs can be tuned via magnetic fields and the drive current, neither approach is conducive to individual SHNO control in large arrays. Here, we demonstrate electrically gated W/CoFeB/MgO nano-constrictions in which the voltage-dependent perpendicular magnetic anisotropy tunes the frequency and, thanks to nano-constriction geometry, drastically modifies the spin-wave localization in the constriction region resulting in a giant 42% variation of the effective damping over four volts. As a consequence, the SHNO threshold current can be strongly tuned. Our demonstration adds key functionality to nano-constriction SHNOs and paves the way for energy-efficient control of individual oscillators in SHNO chains and arrays for neuromorphic computing.
自旋霍尔纳米振荡器（SHNOs）是新兴的自旋电子器件，用于微波信号生成以及基于振荡器的神经形态计算，它具有纳米级尺寸、快速且超宽的微波频率可调性、与CMOS兼容以及强大的非线性特性，能够在链状和二维阵列中实现强大的大规模相互同步。虽然SHNOs可以通过磁场和驱动电流进行调谐，但这两种方法都不利于在大型阵列中对单个SHNO进行控制。在此，我们展示了电门控的W/CoFeB/MgO纳米缩颈结构，其中电压依赖的垂直磁各向异性可调节频率，并且由于纳米缩颈的几何结构，会极大地改变缩颈区域中的自旋波局域化，从而在四伏电压范围内有效阻尼产生高达42%的巨大变化。因此，SHNO的阈值电流可以得到强烈调谐。我们的演示为纳米缩颈SHNOs增添了关键功能，并为神经形态计算中SHNO链和阵列中单个振荡器的节能控制铺平了道路。
