Domain theory and simulation of micromagnetic dynamics

在这个项目中，铁磁性的唯象连续介质理论被应用于描述薄膜元件和类似的小结构中的磁化动力学，这些薄膜元件和类似的小结构在场脉冲下被切换。这种结构的数值模拟将发展一种新的方法，即在磁化本身的时间演化过程中，用虚拟的快速动力学来处理偶极杂散场。这种数值模拟技术将被热噪声扩展，以允许对热激活过程的模拟。该方法有望为那些仍然比时间分辨磁光方法实验观察到的系统更小的系统提供详细的动力学模拟。因此，将开发一种计算过渡路径的技术，该技术将允许在更大系统的纯进动、非耗散动力学的限制下重建开关模式。将探索这种转变路径方法在分析热激活过程中的潜力。部分，简单的磁化过程，既来自较大系统的实验，也来自完整的动态模拟，将根据简化的磁域动力学理论进行分析。

For this project, phenomenological continuum theory of ferromagnetism is applied to describe magnetization dynamics in film elements and similar small structures, that are switched under field pulses. A new method for numerical modelling such structures will be developed treating the dipolar stray-field by fictitious fast dynamics during the time evolution of the magnetization itself. This numerical simulation technique will be extended by thermal noise to allow also simulations of thermally activated processes. The method is expected to yield detailed dynamical simulations for systems that are still smaller than those experimentally observed by time-resolved magneto-optical methods. Therefore, a technique for calculations of transition paths will be developed that shall allow the reconstruction of switching modes in the limit of purely precessional, non-dissipative dynamics for larger systems. The potential of such a transition path method for analysis of thermally activated processes will be explored. Partial, simple magnetization processes, both from experiments for larger systems and from full dynamic simulations will be analysed in terms of simplified domain dynamics theories.