MICROMAGNETIC STRUCTURES OF TRACK-CENTER AND TRACK-EDGE TRANSITIONS RECORDED IN ISOTROPIC LONGITUDINAL THIN-FILM MEDIA WITH A THIN-FILM HEAD

Lorentz transmission electron microscopy was used to image micromagnetic structures near track-center and track-edge transitions recorded in isotropic longitudinal CoCrTa/Cr thin film media with a 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 decrease in the gradient of the head field.