Theory for a dissipative droplet soliton excited by a spin torque nanocontact
Theory for a dissipative droplet soliton excited by a spin torque nanocontact
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DOI：
10.1103/physrevb.82.054432
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发表时间：
2010-08-30
影响因子：
3.7
通讯作者：
Keller, Mark W.
中科院分区：
文献类型：
--
作者：
Hoefer, M. A.;Silva, T. J.;Keller, Mark W.
当自由层具有足够大的垂直各向异性时，预测在自旋扭矩振荡器中将形成一种不同类型的孤立波。这种结构是Ivanov和Kosevich在1977年最初研究的保守液滴孤子的耗散版本，在这种结构中，自旋扭矩抵消了否则将摧毁模式的阻尼。用渐近方法导出了耗散液滴成核和维持的垂直各向异性强度和外加电流的条件。用数值方法验证了液滴对实验中可能发生的各种扰动的稳定性，包括外加磁场的倾斜、非零自旋扭矩不对称和非平凡的Oersted场。在某些条件下，液滴会经历漂移不稳定，在这种情况下，液滴会远离纳米接触而传播，然后被阻尼破坏。
A distinct type of solitary wave is predicted to form in spin torque oscillators when the free layer has a sufficiently large perpendicular anisotropy. In this structure, which is a dissipative version of the conservative droplet soliton originally studied in 1977 by Ivanov and Kosevich, spin torque counteracts the damping that would otherwise destroy the mode. Asymptotic methods are used to derive conditions on perpendicular anisotropy strength and applied current under which a dissipative droplet can be nucleated and sustained. Numerical methods are used to confirm the stability of the droplet against various perturbations that are likely in experiments, including tilting of the applied field, nonzero spin torque asymmetry, and nontrivial Oersted fields. Under certain conditions, the droplet experiences a drift instability in which it propagates away from the nanocontact and is then destroyed by damping.