Preparation of a magneto‐optical disk using a rare earth–transition metal alloy target

We have evaluated the basic performances of TbFeCo and TbCo alloy targets for the sputter deposition of magneto‐optical recording media. The composition of the sputtered film shifts from the original one of the target, and the Tb concentration in the sputtered film is always reduced by about 6 at. % in both alloy targets. Sputtered films were all perpendicular magnetic film with a squareness ratio (ratio of residual magnetization to saturation magnetization) of 1, and the residual Kerr rotation angle was about 20’ min. The measurements indicate no change in the sputtering characteristics of the targets after more than 100 h of use.