Computations of the micromagnetic dynamics in domain walls

Abstract

A numerical model was developed to compute the temporal and spatial variations of the detailed micromagnetic structures of domain walls by numerical integration of the Landau-Lifshitz-Gilbert equation. The fundamental interactions due to anisotropy, exchange, and demagnetization are included. Preliminary results of the structure of a planar domain wall indicate that the wall width is much larger near the film surface than at the center of the film, because the demagnetization fields are significant near the surface and the side boundaries of the domain wall. The instabilities of the numerical integration of the LLG equation are investigated. Several methods were developed to cope with the stiffness which arises when the damping parameter becomes small. The effects of nondimensional film thickness and anisotropy parameters are similar and are less than 10%, with these parameters varying by a factor of 2. On the other hand, the effects of an ion-implantation layer in the film on the wall structure are found to be very significant.