Twisted domain wall structure in bubble films

Abstract

Because of the magnetic surface charge, the wall magnetization is ``twisted'' into a direction almost perpendicular to the wall plane near the film surface. The width and energy of such walls and the twist angle have been calculated by a variational method for uniaxial anisotropy and stationary plane walls. For very thick films (film thickness ≫ wall width in an infinite medium), the reciprocal wall width and the wall energy are smaller than the values for an untwisted wall by approximately a factor (1 − 0. 65σ)½, where σ=4πM0/Ha, M0 being the saturation magnetization and Ha the uniaxial anisotropy field.