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arXiv 0805.0147nlin.CDcond-mat.mtrl-scinlin.PS
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电流驱动下长纳米磁体的混沌自旋动力学

Chaotic Spin Dynamics of a Long Nanomagnet Driven by a Current

Yueheng Lan, Y. Charles Li

摘要:

我们研究了由电流驱动的长纳米磁体的自旋动力学。在只有直流电流的情况下,自旋动力学具有复杂的吸引子分岔图。一种类型的吸引子是弱混沌。另一方面,在只有交流电流的情况下,自旋动力学有一个相当简单的吸引子分岔图。也就是说,对于小吉尔伯特阻尼,当交流电流低于临界值时,吸引子是极限环;高于临界值,吸引子是混沌的(湍流的)。对于正常的吉尔伯特阻尼,吸引子总是一个极限环的物理感兴趣的范围内的交流电流。我们还开发了Melnikov积分理论的理论预测的混沌的发生。我们的Melnikov预测似乎在DC情况下表现得很好。在AC的情况下,我们的Melnikov预测似乎预测瞬态混沌。持续的混沌吸引子似乎有额外的支持,从参数共振导致的湍流状态。

英文摘要:

We study the spin dynamics of a long nanomagnet driven by an electrical current. In the case of only DC current, the spin dynamics has a sophisticated bifurcation diagram of attractors. One type of attractors is a weak chaos. On the other hand, in the case of only AC current, the spin dynamics has a rather simple bifurcation diagram of attractors. That is, for small Gilbert damping, when the AC current is below a critical value, the attractor is a limit cycle; above the critical value, the attractor is chaotic (turbulent). For normal Gilbert damping, the attractor is always a limit cycle in the physically interesting range of the AC current. We also developed a Melnikov integral theory for a theoretical prediction on the occurrence of chaos. Our Melnikov prediction seems performing quite well in the DC case. In the AC case, our Melnikov prediction seems predicting transient chaos. The sustained chaotic attractor seems to have extra support from parametric resonance leading to a turbulent state.

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。

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