论文标题

小部分landau-lifshitz-gilbert方程

The fractional Landau-Lifshitz-Gilbert equation

论文作者

Verstraten, Robin C., Ludwig, Tim, Duine, Rembert A., Smith, Cristiane Morais

论文摘要

磁矩或旋转的动力学对技术的应用非常感兴趣。因此,这些系统中的耗散对于提高设备效率(例如Spintronics提出的设备效率)至关重要。 Landau-Lifshitz-Gilbert(LLG)方程式被广泛地假定磁场中的大型自旋,其中包括现象学吉尔伯特阻尼。在这里,我们将大型旋转到浴缸中,并使用Caldeira-Leggett型号来得出低频范围的通用(非)欧姆阻尼术语。这导致了分数LLG方程,其中一阶导数吉尔伯特阻尼被$ s \ ge 0 $的分数导数所取代。我们表明,参数$ s $可以从铁磁共振实验确定,在该实验中,共振频率和线宽不再与有效的磁场强度线性缩放。

The dynamics of a magnetic moment or spin are of high interest to applications in technology. Dissipation in these systems is therefore of importance for improvement of efficiency of devices, such as the ones proposed in spintronics. A large spin in a magnetic field is widely assumed to be described by the Landau-Lifshitz-Gilbert (LLG) equation, which includes a phenomenological Gilbert damping. Here, we couple a large spin to a bath and derive a generic (non-)Ohmic damping term for the low-frequency range using a Caldeira-Leggett model. This leads to a fractional LLG equation, where the first-order derivative Gilbert damping is replaced by a fractional derivative of order $s \ge 0$. We show that the parameter $s$ can be determined from a ferromagnetic resonance experiment, where the resonance frequency and linewidth no longer scale linearly with the effective field strength.

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