The optimization of sputtered Co-Cr layered medium for maximum areal density

The layered Cr-Co structure has shown itself suitable as a thin-film medium for longitudinal saturation recording on magnetic disks. The coercivity and remanence-thickness product of this medium can be varied over a wide range by adjusting the thicknesses of the Cr and Co layers. The approximate theory of Williams and Comstock is invoked to select magnetic parameters for maximum areal density. The theory indicates the direction future medium development should take and, further, emphasizes the overriding importance of reducing head-gap length, flying height and medium thickness. Experimental results show the improvement in areal density attainable by increasing thickness of the Cr underlayer and by adding additional layer pairs of Cr and Co.