Track edge phenomena in thin film longitudinal media

Abstract

Isolated transitions, recorded with a thin-film inductivc head on isotropic film media and read with a magnetoresistive (MR) sensor can exhibit waveform distortions, characterized by a shift of the base line between readback pulses. The amount of this base-line shift (BLS) increases with increasing write current, decreasing trackwidth and decreasing medium coercivity. The source of the DLS is shown experimentally to be localized at the track edges. A model, based on the creation of magnetic dipoles along each cdge of a data track is proposed to explain the observed waveform deformation. Quantitative measurcments of the

Track-edge read-write effect of inductive/MR dual element heads

“…3. The erase band at the side away fiom the transition region has a dipolar magnetic charge distribution oriented towards the cross-track direction, in good agreement with previous hypothesis [2], micromagnetic simulation [7] and MFM imaging studies [8]. For a fully track-trimmed writer, this track-edge phenomenon is much less pronounced and the side writing is significantly reduced [2].…”

“…2). In this case, neither type of MR heads exhibits any base-line shift due to the absence of the dipolar track-edge charge distribution [2]. The difference in the positive and negative pulse amplitudes are caused by different amount of sensor biasing for the overlay and the contiguous junction MR heads.…”

“…3). The overlay MR head, on the other hand, does pick up spurious side track information, resulting in the usual base-line shift [2]. Fig.…”

“…On the component level, the MR read head, the thin-film writer, and the thin-film disk media, all have to be optimized with respect to each other in order to achieve the best system level performance. In this work, the effect of side-writing from the thin-film writer [2] on the read-back properties of the MR heads is investigated by recording physics analysis and micromagnetic simulation. A typical merged read/write dual element head structure is shown in Fig.…”