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arXiv 2103.09888math.NAcs.NA
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考虑惯性效应的Landau-Lifshitz-Gilbert方程的数值分析

Numerical analysis of the Landau-Lifshitz-Gilbert equation with inertial effects

Michele Ruggeri

摘要:

我们考虑惯性Landau-Lifshitz-Gilbert方程(iLLG)的数值逼近,该方程描述了铁磁材料在亚皮秒时间尺度下的磁化动力学.我们提出并分析了两个完全离散的数值方案:第一种方法是基于重新制定的问题作为一个线性约束变分公式的线速度。第二种方法利用了一个重新制定的问题作为一个一阶系统的磁化和角动量的时间。这两种方案都是隐式的,基于一阶有限元,并在底层网格的顶点处生成满足iLLG的单位长度约束的近似。对于这两种方法,我们证明了收敛的逼近问题的弱解。数值实验验证了理论分析的正确性,并表明了该方法在超快磁过程模拟中的适用性。

英文摘要:

We consider the numerical approximation of the inertial Landau-Lifshitz-Gilbert equation (iLLG), which describes the dynamics of the magnetization in ferromagnetic materials at subpicosecond time scales. We propose and analyze two fully discrete numerical schemes: The first method is based on a reformulation of the problem as a linear constrained variational formulation for the linear velocity. The second method exploits a reformulation of the problem as a first order system in time for the magnetization and the angular momentum. Both schemes are implicit, based on first-order finite elements, and generate approximations satisfying the unit-length constraint of iLLG at the vertices of the underlying mesh. For both methods, we prove convergence of the approximations towards a weak solution of the problem. Numerical experiments validate the theoretical results and show the applicability of the methods for the simulation of ultrafast magnetic processes.

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