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arXiv 1002.4958cond-mat.mes-hallcond-mat.stat-mech
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随机Landau-Lifshitz-Gilbert方程中的相关效应

Correlation Effects in the Stochastic Landau-Lifshitz-Gilbert Equation

Thomas Bose, Steffen Trimper

摘要:

当磁矩的进动运动附加单轴各向异性并由有限关联时间$τ$的乘性耦合随机场驱动时,我们分析了Landau-Lifshitz-Gilbert方程.自旋波分量的平均值提供了自旋波色散关系及其阻尼受到确定性吉尔伯特阻尼参数$α$、随机力$D$的强度及其时间范围$τ$的强烈影响。通过推导联合概率函数的演化方程,可以在低关联时间极限下计算自旋-自旋-关联函数。稳定性分析使我们能够找到的相位图内的$α-D$平面为不同值的$τ$阻尼自旋波解决方案是稳定的。即使对于零确定性吉尔伯特阻尼的磁振子提供有限的寿命。我们检测到一个参数范围内的确定性和随机阻尼机制能够相互补偿导致无阻尼自旋波。的发病的特征在于由一个临界值的相关时间。$τ$的增强导致关联函数的振荡增加。

英文摘要:

We analyze the Landau-Lifshitz-Gilbert equation when the precession motion of the magnetic moments is additionally subjected to an uniaxial anisotropy and is driven by a multiplicative coupled stochastic field with a finite correlation time $τ$. The mean value for the spin wave components offers that the spin-wave dispersion relation and its damping is strongly influenced by the deterministic Gilbert damping parameter $α$, the strength of the stochastic forces $D$ and its temporal range $τ$. The spin-spin-correlation function can be calculated in the low correlation time limit by deriving an evolution equation for the joint probability function. The stability analysis enables us to find the phase diagram within the $α-D$ plane for different values of $τ$ where damped spin wave solutions are stable. Even for zero deterministic Gilbert damping the magnons offer a finite lifetime. We detect a parameter range where the deterministic and the stochastic damping mechanism are able to compensate each other leading to undamped spin-waves. The onset is characterized by a critical value of the correlation time. An enhancement of $τ$ leads to an increase of the oscillations of the correlation function.

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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