Side-writing phenomena in isotropic film media

The isolated readback pulses of magnetoresistive (MR) heads on isotropic film media have been reported to exhibit base-line shifts. We have further observed that for piggyback MR (PMR) heads with thick pole-tip write elements operating at high write currents, an additional base-line shift occurs, thereby producing dual-base-line shifts. This second base-line shift results in anomalous signal-amplitude variations as the transition density increases. Moreover, the onset of the second base-line shift occurs ahead of the readback pulses at a distance equal to the trailing-pole thickness. We attribute the second base-line shift to the trailing-pole side writing, which modifies the magnetic dipole distribution along the track edges prior to the transitions at a distance equal to the trailing-pole thickness.