5 Gb/in2 recording demonstration with conventional AMR dual element heads & thin film disks

Abstract

We have successfully demonstrated magnetic recording at an areal density of 5 Gb/in2 and a data rate of 10 MB/s using narrow track dual element heads with conventional AMR sensors and low noise Co alloy thin film disks. In this work, the target densities of 240K bpi x 21K tpi were achieved by a combination of narrow track and low-flying technologies. The write and read head trackwidths were reduced to submicron dimensions, with high moment pole-tips to maintain good writability. At the same time, magnetic spacing was substantially reduced by using low-flying airbearing surface designs. Finally, significant signal-to-noise improvements were attained with the development of high sensitivity AMR read heads and very low noise thin film media. Recording tests showed satisfactory writability in terms of overwrite and hard-transitions from the submicron width write heads. Readback yielded symmetrical signals close to ImV/ym and rolloff measurements yielded 50% densities as high as 7000 fc/mm. Track profile and microprofile measurements showed write and read trackwidths to be around 1. 2 urn and 0. 7 jim respectively, with tight side-writing and sidereading characteristics. An overall assessment of the parametric recording results suggested an areal density feasibility of around 5 Gb/in2. This projection was confirmed by error rate testing at 10 MB/s using a PRML channel with digital filter and write precompensation. At low ontrack errors of 10~' - 10"9 without error correction codes, linear densities of -240K bpi and optimized track pitches of ~1. 2 iim were achieved, corresponding to areal densities of 5 Gb/in2. © 1997 IEEE.