Frequency transition of spin-torque oscillator under the magnetic-field pulse in nanosecond range
Frequency transition of spin-torque oscillator under the magnetic-field pulse in nanosecond range
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纳秒级磁场脉冲下自旋扭矩振荡器的频率转变
DOI：
10.1063/1.3549592
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发表时间：
2011
影响因子：
3.2
通讯作者：
R. Sato
中科院分区：
文献类型：
--
作者：
T. Nagasawa;H. Suto;K. Kudo;K. Mizushima;R. Sato
我们报告了纳秒范围内磁场脉冲下自旋扭矩振荡器（STO）频率转变的时域研究。我们制造了由 MgO 基隧道结和 CoFeB 自由层组成的柱状结构 STO 器件。使用实时示波器（40 GS/秒）获得 STO 的单次波形。首先，我们测量了波形的电流依赖性，以研究振荡的时域稳定性。随着施加到STO的直流电流的增加，振荡状态按以下顺序连续变化：热波动、间歇性非稳态振荡、稳态振荡和混沌振荡。接下来，我们测量了 STO 对上升时间为 0.5 ns、持续时间为 10 ns、幅度为 60 Oe 的磁场脉冲的响应。在这次测量中，振荡状态保持在上述稳定状态，频率~3.5 GHz，谱线宽度~50 MHz。在存在磁力的情况下...
We report a time domain study of the frequency transition of spin-torque oscillator (STO) under the magnetic-field pulse in nanosecond range. We fabricated the pillar-structured STO devices consisting of MgO-based tunnel junctions with CoFeB free layers. Single-shot waveforms of the STO were obtained using a real-time oscilloscope (40 GS/sec). First, we measured current dependence of the waveform to investigate the time-domain stability of the oscillation. With the increase in the dc current applied to the STO, the oscillation state changed continuously in the following order: thermal fluctuation, intermittent unsteady oscillation, steady oscillation, and chaotic oscillation. Next, we measured the response of the STO to the magnetic-field pulse with a rise time of 0.5 ns, a duration time of 10 ns, and an amplitude of 60 Oe. In this measurement, the oscillation state was kept in the above-mentioned steady state with the frequency ∼3.5 GHz and the spectral linewidth ∼50 MHz. In the presence of the magnetic-...