The effect of thickness in high bit density recording on particulate and plated disks

Progress towards higher performance digital magnetic recording disk systems is closely related to the development of thinner, better dispersed and oriented particulate coatings or of very thin plated coatings applied to flatter and smoother substrates. Today, the state of the art for particulate coatings is slightly under 1μm in thickness, whereas plated coatings can be made down to nano meter range. In this paper we present a theoretical study of the effect of thickness (in the range of m for particulate coatings and 25-175 nm for plated coatings) on the signal response, the resolutions, and the peakshift of particulate and plated disk coatings for different bit densities in the range of 2500-5000 bits/cm. The study was performed by using an iterative self-consistent simulation model which has been shown to provide good agreement with experimental measurements. We conclude that the thinner plated surfaces offer large advantages in signal amplitude, resolution, and peak shift over the thicker particulate coatings. At the highest bit densities examined (5000 bits/cm) even the plated coatings have to be extremely thin (50nm or less) in order to provide acceptable peakshift for reliable signal detection.