Domain theory and simulation of micromagnetic dynamics

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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.