Domain structures in thin-film discrete magnetic tracks

Abstract

The magnetic domain structure and recording characteristics of thin-film discrete tracks, physically etched in Co-alloy thin-film disks. have been studied. The micromagnetic characteristics of recorded transitions written on tracks with widths in the range 0.5 to 10/lm at bit densities of 200 to 1000 fc/mm were imaged using Lorentz electron microscopy both in the Fresnel (phase contrast) and the Foucault (diffraction contrast) modes. Previous work has shown that signal and media noise scale linearly with discrete track width to submicron dimensions. This scaling behavior can be explained by the uniformity of the domain wall structure across the track width revealed by Lorentz microscopy. No unusual domain structures are found at the edges, in contrast to conventional recording on continuous films where complex domain structures have been observed at the edges of the written tracks. Interpretation of the images provides information about the bit definition, transition zones and the fringing fields as a function of the recording frequency and the discrete track width. © 1988 IEEE