A Study of the Thinner Cr Underlayer in Co-Alloy/Cr for Rigid Disk

This work reports the effect of a thinner Cr underlayer in a longitudinal metal medium consisting of Co alloy on a Cr underlayer. Media with a thinner Cr underlayer exhibit improved signal-to-noise characteristics compared to media with a thicker Cr underlayer. This is a consequence of an increased saturation magnetic flux density Bs and squareness S, and decreased noise N. We think that the change in Bs is influenced by the level of diffusion between the Cr underlayer and the Co alloy film layer, that the change in S is affected by changes in the Co crystalline orientation, and that changes in N are due to changes in grain size.