12 Gb/in² recording demonstration with SV read heads & conventional narrow pole-tip write heads

Abstract

We have successfully demonstrated magnetic recording at areal densities as high as 12 Gb/in2 at a data rate of 14-15 MB/s using separate spin-valve read heads and narrow pole-tip inductive write heads on low noise Co alloy thin film disks. In this work, the nominal target densities were 350 Kbpi × 34 Ktpi. To make these densities possible, large signal-to-noise gains were attained with the use of high performance spin-valve read heads and low noise thin film media. At the same time, very narrow track write heads were designed and fabricated by extending conventional photolithographic techniques. Finally, small magnetic spacings between the head and the disk were attained with low flying ABS designs and improved head & disk surfaces. Recording tests showed satisfactory writability and large readback signal of around 2 mV/μ.m. The 50% rolloff densities were as high as 10 Kfc/mm, while the write and read trackwidths were as narrow as 0.7 and 0.5 μm respectively. An overall assessment of the parametric recording results indicated an areal density capability of at least 10 Gb/in2. This projection was confirmed by error rate testing with an EPR-4 channel, where very low ontrack errors of 10-10-10-9 were achieved at 315-380 Kbpi. Furthermore, squeeze measurements revealed well-defined 747 behavior with offtrack maxima at 0.7-0.8 μm trackpitch. The product of linear and track densities for the write and read head combinations tested indeed showed that an areal density of 11-12 Gb/in2 has been achieved. © 1999 IEEE.