Performance study & analysis of dual-element head on thin-film disk for gigabit-density recording

Abstract

Inductive-write And MR-read dual-element heads with very narrow tracks and gaps have been designed, fabricated and tested on thin film media of high coercivity and squareness. Results not only show excellent writeability at modest write currents, but also the existence of a narrow region of optimum write current, limited by the onset of self-erasure by the write head at high write currents. This leads to significant degradations of overwrite, signal amplitude, trackwidth, linear resolution and disk noise induced peak-jitters. Also, our work shows a peak-jitter approach to be useful in characterizing many aspects of recording performance. A peak-jitter evaluation of signal-to-noise behavior, for example, reveals not only satisfactory overall performance, but also the dominance of disk noise as well as a concentration of the disk noise at the track edges. Also, peak-jitter evaluations of offtrack and squeeze behavior demonstrate clearly the narrow track capabilities of these recording heads for high areal density operation. © 1990 IEEE