Transitional domain wall structure in Permalloy magnetic films with decreasing thickness

The transitional wall structure of a domain wall in Permalloy films in the thickness range of 5.12 /spl mu/m to 0.16 /spl mu/m is investigated using direct integration of the Landau-Lifshitz-Gilbert equation in a three dimensional Cartesian lattice. The expected stray-field-free structure containing a Bloch wall in the center, Neel caps at the surfaces with a vortex structure on one side of the wall was found for films thicker than 2.56 /spl mu/m. However, the region through the thickness where the /spl nabla//sup /spl omega///spl middot/M/sup /spl mu// across the wall is zero (Bloch wall) was of small extent below 1 /spl mu/m thickness. Neel caps with opposite chirality existed at all thickness investigated down to 0.16 /spl mu/m. The vortex is characterized by an overshoot in the polar angle /spl theta/ out of the plane of the material. Two maximum values of the overshoot were observed for films 2.56 /spl mu/m and thicker. They were located near the film surface under the Neel caps. Thinner films had only one maximum located in the center of the material. The maximum overshoot was a function of thickness varying from 100 to a maximum value of 340 for the 0.64 /spl mu/m thick sample. As the thickness is decreased to 0.16 /spl mu/m, a residual normal component is observed at the surface near the Neel caps, leading to stray fields at the surface.