Track edge phenomena in thin film longitudinal media

Isolated transitions recorded with a thin-film inductive head on thin-film isotropic media and read with a magnetoresistive sensor can exhibit waveform distortions characterized by a shift of the base line between readback pulses. The amount of the base-line shift (BLS) increases with increasing write current, decreasing trackwidth, and decreasing medium coercivity. The source of the BLS is shown experimentally to be localized at track edges. A model based on the creation of magnetic dipoles along each edge of the data track is proposed to explain the observed waveform deformation. The width of the dipole distribution is estimated by deconvolving a measured BLS track profile with a measured readback-sensitivity track profile. Calculated BLS profiles based on this dipole model agree well with the experimental observation