High-performance Co/Pt multilayer magneto-optical disk using ultrathin seed layers

Abstract

We have prepared high-performance disks based on Co/Pt multilayers using ultrathin seed layers. Both crystalline (such as ZnO) and amorphous [such as indium-tin-oxide (ITO) and Si] materials were used as seed layers. We found that very thin layers of these materials enhance coercivity, squareness of the Kerr loop, and perpendicular anisotropy of the Co/Pt superlattices. These beneficial effects are obtained with a seed layer as thin as 0.2 nm. This is incontrast with the earlier presumptions that indicated much thicker layers, about 80 nm of crystalline material, were required to improve the texture of the Co/Pt multilayer for sufficient enhancement in the coercivity. Further, the data indicated that disks with amorphous seed layers generally have higher perpendicular anisotropy and lower recording noise as compared to those with crystalline ZnO. We have prepared disks using a thin amorphous ITO seed layer and a simple disk structure: grooved PC/ITO/12[Co/Pt]/lacquer overcoat. The performance of these disks is similar to that a commercial TbFeCo media. This media has potential for low cost manufacturing.