Nonlinear analysis of magnetization dynamics excited by spin Hall effect
Nonlinear analysis of magnetization dynamics excited by spin Hall effect
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DOI：
10.1103/physrevb.91.104406
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发表时间：
2015-02
影响因子：
3.7
通讯作者：
T. Taniguchi
中科院分区：
文献类型：
--
作者：
T. Taniguchi
在对Landau-Lifshitz-Gilbert （LLG）方程进行非线性分析的基础上，研究了自旋霍尔效应在垂直铁磁体中激发自激振荡的可能性。在自振荡状态下，恒定能量曲线进动时自旋力矩提供的能量应等于阻尼耗散。同时，平衡自振荡状态下的自旋力矩和阻尼力矩的电流应大于使初始状态失稳的临界电流。从非线性LLG方程中推导出自旋转移效应提供的能量和阻尼耗散的解析解，发现自旋霍尔系统不满足第二个条件。这表明垂直铁磁体的自激振荡不能仅由自旋霍尔转矩激发。
We investigate the possibility of exciting self-oscillation in a perpendicular ferromagnet by the spin Hall effect on the basis of a nonlinear analysis of the Landau-Lifshitz-Gilbert (LLG) equation. In the self-oscillation state, the energy supplied by the spin torque during a precession on a constant energy curve should equal the dissipation due to damping. Also, the current to balance the spin torque and the damping torque in the self-oscillation state should be larger than the critical current to destabilize the initial state. We find that the second condition in the spin Hall system is not satisfied by deriving analytical solutions of the energy supplied by the spin transfer effect and the dissipation due to the damping from the nonlinear LLG equation. This indicates that the self-oscillation of a perpendicular ferromagnet cannot be excited solely by the spin Hall torque.