Full-spin-wave-scaled stochastic micromagnetism for mesh-independent simulations of ferromagnetic resonance and reversal
Full-spin-wave-scaled stochastic micromagnetism for mesh-independent simulations of ferromagnetic resonance and reversal
复制标题
全自旋波尺度随机微磁学，用于铁磁共振和反转的网格独立模拟
DOI：
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发表时间：
2022
影响因子：
9.7
通讯作者：
T. Schrefl
中科院分区：
文献类型：
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作者：
H. Oezelt;Luman Qu;A. Kovacs;J. Fischbacher;M. Gusenbauer;R. Beigelbeck;D. Praetorius;M. Yano;T. Shoji;A. Kato;R. Chantrell;M. Winklhofer;G. Zimányi;T. Schrefl
在本文中，我们解决了标准随机Landau-Lifshitz-Gilbert （sLLG）模拟通常会产生显示非物理网格大小依赖的结果的问题。造成这一问题的根本原因是在sLLG中忽略了自旋波波动的影响。我们建议用全自旋波尺度随机LLG或FUSSS LLG方法来表示这些波动的影响。在FUSSS LLG中，sLLG模拟的内在参数首先通过缩放因子进行缩放，该缩放因子将自旋波波动整合到网格尺寸，然后使用这些缩放参数进行sLLG模拟。我们通过研究nd2fe14b立方体的铁磁共振（FMR），开发了FUSSS LLG。相对于sLLG，标称缩放大大降低了对网格尺寸的依赖。然后，我们使用这种修改后的缩放对我们的FUSSS LLG进行了三次测试和验证。(1)我们研究了同样的FMR，但包含了静磁场。(2)模拟了nd2fe14b立方体的总磁化强度。(3)研究了立方体的有效矫顽力场、温度场和扫速场。在这三种情况下，我们发现FUSSS LLG基本上提供了与网格大小无关的结果，这比未缩放的sLLG更好地跟踪了理论期望。在这些成功验证的激励下，我们提出FUSSS LLG为精确、高精度的硬永磁体微磁性建模提供了显著的、定性的进展。
In this paper, we address the problem that standard stochastic Landau-Lifshitz-Gilbert (sLLG) simulations typically produce results that show unphysical mesh-size dependence. The root cause of this problem is that the effects of spin-wave fluctuations are ignored in sLLG. We propose to represent the effect of these fluctuations by a full-spin-wave-scaled stochastic LLG, or FUSSS LLG method. In FUSSS LLG, the intrinsic parameters of the sLLG simulations are first scaled by scaling factors that integrate out the spin-wave fluctuations up to the mesh size, and the sLLG simulation is then performed with these scaled parameters. We developed FUSSS LLG by studying the Ferromagnetic Resonance (FMR) in Nd 2 Fe 14 B cubes. The nominal scaling greatly reduced the mesh size dependence relative to sLLG. We then performed three tests and validations of our FUSSS LLG with this modified scaling. (1) We studied the same FMR but with magnetostatic fields included. (2) We simulated the total magnetization of the Nd 2 Fe 14 B cube. (3) We studied the effective, temperature- and sweeping rate-dependent coercive field of the cubes. In all three cases, we found that FUSSS LLG delivered essentially mesh-size-independent results, which tracked the theoretical expectations better than unscaled sLLG. Motivated by these successful validations, we propose that FUSSS LLG provides marked, qualitative progress towards accurate, high precision modeling of micromagnetics in hard, permanent magnets.