Ultrafast remagnetization processes: stochastic dynamics study using the correlated random noise

该项目的第一个目标是发展适用于研究各种物理系统中的超快再磁化过程的新的数值方法。这里的基本问题是，在与超快动力学相关的时间尺度上，随机方程中的随机噪声不能再被认为是不相关的。因此，我们打算构造一种新的有效的方法来求解随机微磁方程，同时考虑随机场的空间和时间相关性。利用在第一个项目阶段开发的方法，我们将考虑所有相关的磁相互作用和热激活，模拟平衡磁化涨落和不可逆的非平衡再磁化过程。我们的模拟必须提供有关上述过程的详细信息。这意味着，基于我们的结果，应该可以计算大多数实验可测量的量，以便能够将我们的结果与通过当前可用的方法如布里渊散射、SEMPA、Kerr光谱、FMR等获得的实验数据进行直接比较。还计划将我们的结果与基于离散晶格模型进行的数值模拟进行比较。

The first goal of this project is the development of new numerical methods suitable for the study of ultrafast remagnetization processes in various physical systems. The basic problem here is that on the time scales relevant for the ultrafast dynamics the random noise present in stochastic equations can not be considered any more as uncorrelated. Hence we intend to construct new efficient methods for the solution of the stochastic micromagnetic equations taking into account both space and time correlations of random field. Using the methods developed during the first project stage we are going to simulate - taking into account all relevant magnetic interactions and thermal activation - the equilibrium magnetization fluctuations and irreversible non-equilibrium remagnetization processes. Our simulations must provide the detailed information about the processes mentioned above. This means that, basing on our results, it should be possible to calculate most of the experimentally measurable quantities to enable a direct comparison of our results with experimental data obtained via the currently available methods like the Brillouin scattering, SEMPA, Kerr spectroscopy, FMR etc. Comparison of our results with numerical simulations performed on the basis of discrete lattice models is also planned.