周期磁场中自旋阀柱的分岔与混沌
Bifurcation and chaos in spin-valve pillars in a periodic applied magnetic field
摘要：
我们研究了自旋阀柱中使用的均匀纳米尺度铁磁薄膜中宏观磁化矢量的分岔和混沌现象。基本的动力学描述的广义Landau-Lifshitz-Gilbert（LLG）方程。LLG方程在复杂的球极投影下具有特别吸引人的形式，其中所施加的场和自旋电流引起的转矩的定性等价是透明的。最近，Zhang和Li利用通过具有恒定极化方向和周期性变化幅度的柱的自旋极化电流，由于自旋转移矩效应，已经确定了这种自旋矢量的混沌行为。在本文中，我们表明，可以实现相同的动力学行为，使用一个周期性变化的外加磁场，在存在一个恒定的直流磁场和恒定的自旋电流，这在技术上是更加可行的，并证明了数值系统中的混沌动力学的无限薄膜。此外，应注意的是，在存在非零晶体各向异性场的情况下，混沌动力学在低得多的自旋电流和DC施加场的幅度下发生。
英文摘要：
We study the bifurcation and chaos scenario of the macro-magnetization vector in a homogeneous nanoscale-ferromagnetic thin film of the type used in spin-valve pillars. The underlying dynamics is described by a generalized Landau-Lifshitz-Gilbert (LLG) equation. The LLG equation has an especially appealing form under a complex stereographic projection, wherein the qualitative equivalence of an applied field and a spin-current induced torque is transparent. Recently chaotic behavior of such a spin vector has been identified by Zhang and Li using a spin polarized current passing through the pillar of constant polarization direction and periodically varying magnitude, owing to the spin-transfer torque effect. In this paper we show that the same dynamical behavior can be achieved using a periodically varying applied magnetic field, in the presence of a constant DC magnetic field and constant spin current, which is technically much more feasible, and demonstrate numerically the chaotic dynamics in the system for an infinitely thin film. Further, it is noted that in the presence of a nonzero crystal anisotropy field chaotic dynamics occurs at much lower magnitudes of the spin-current and DC applied field.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
