Effect of radial curvature of magnetic media on glide avalanche

Spacing loss due to micro-waviness and curvature effects in the radial direction of a disk was investigated via numerical simulations and measurements. New techniques based on interferometry and laser scanning were employed to measure radius of curvature (ROC) and to reconstruct the profiles at the outer edge of a disk. A good correlation between ROC values and fly height degradation was obtained, and ROC less than 50 m clearly showed the deterioration in fly height by as much as 1.5 nm. The new measurement techniques proved to be an important means to improve substrate manufacturing processes.