Micromagnetic structures of track-center and track-edge transitions recorded in isotropic longitudinal thin film media with a thin film head

Lorentz transmission microscopy was used to image micromagnetic structures near track-center and track-edge transitions recorded in isotropic longitudinal CoCrTa/Cr thin-film head. The superposition of over-focused and under-focused Lorentz Fresnel-mode images yielded clear magnetic microstructures which exhibited both clockwise and counterclockwise magnetic vortices. Transitions were wider near track edges than at track centers. Some vortices along the center of recorded transitions exhibited alternating senses of rotation and some formed zigzag or sawtooth walls. The center line of a transition showed a curvature near the track edge corresponding to the shape of the head field contour line. In addition, the length of a transition increased as the head-to-medium spacing was increased, as might be expected from the corresponding decreased in the gradient of the head field