Origin of Nonlinear Damping Due to Mode Coupling in Auto-Oscillatory Modes Strongly Driven by Spin-Orbit Torque
Origin of Nonlinear Damping Due to Mode Coupling in Auto-Oscillatory Modes Strongly Driven by Spin-Orbit Torque
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DOI：
10.1103/physrevapplied.17.064047
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发表时间：
2022-06-24
影响因子：
4.6
通讯作者：
Hammel, P. Chris
中科院分区：
文献类型：
--
作者：
Lee, Inhee;Zhang, Chi;Hammel, P. Chris
我们调查的非线性阻尼的物理起源，由于模式之间的耦合驱动的自旋-轨道扭矩压缩Pt/Py（坡莫合金）异质结构的自振荡模式通过检查依赖于温度和外加磁场的方向。我们观察到从总振荡功率中提取的自振荡模式的非线性阻尼作为驱动电流的函数的转变，这与几种模式之间的功率重新分配的开始以及所有单个模式中从线宽变窄到线宽变宽的交叉相一致。这表明激活的另一个弛豫过程中的非线性磁振子-磁振子散射的模式。我们还发现，非线性阻尼和阈值电流的模式相互作用阻尼制度在高驱动电流后过渡是温度无关的，这表明模式耦合主要发生通过非热磁振子散射过程通过偶极或交换相互作用，而不是热激发磁振子介导的散射。这一发现提出了一个有前途的途径，克服目前的限制，有效地控制两个高度非线性磁振荡器之间的相互作用，以防止模式串扰或模间能量转移，并加深了理解复杂的非线性自旋动力学多模自旋波系统。
We investigate the physical origin of nonlinear damping due to mode coupling between several auto-oscillatory modes driven by spin-orbit torque in constricted Pt/Py(permalloy) heterostructures by examining the dependence of the auto-oscillation on the temperature and the applied field orientation. We observe a transition in the nonlinear damping of the auto-oscillation modes extracted from the total oscillation power as a function of the drive current, which coincides with the onset of power redistri-bution among several modes and the crossover from linewidth narrowing to linewidth broadening in all individual modes. This indicates the activation of another relaxation process by nonlinear magnon-magnon scattering within the modes. We also find that both nonlinear damping and the threshold current in the mode-interaction damping regime at high drive current after transition are temperature independent, suggesting that the mode coupling occurs dominantly through a nonthermal magnon-scattering process via a dipole or exchange interaction rather than thermally excited magnon-mediated scattering. This finding presents a promising pathway toward overcoming the current limitations of efficiently controlling the inter-action between two highly nonlinear magnetic oscillators to prevent mode crosstalk or intermode energy transfer and deepens the understanding of complex nonlinear spin dynamics in multimode spin-wave systems.