Solving Micromagnetic Problems. Towards an Optimal Numerical Method

Abstract

Various possibilities to improve numerical methods for the solution of micromagnetic problems are studied. Special attention is paid to the computation of the non-local energy part — the stray field energy. The evaluation of a scalar magnetic potential using a FFT algorithm turns out to be the most powerful and reliable acceleration technique. A Landau-Lifshitz-like equation of motion is used to drive the system towards the equilibrium state, where the effective field appearing in this equation is used at the same time to calculate and monitor the system energy during the iteration process. Two classical two-dimensional micromagnetic problems in low-anisotropy materials are solved with the methods described above: the field-induced transition between asymmetric Bloch and Néel walls in a thin film, and the structure of the transition line inside an infinitely extended Bloch wall in a uniaxial material.