A Study of Perpendicular Magnetic Recording Media With an Exchange Control Layer

Exchange coupled composite (ECC) media have been proposed as a way to facilitate writing of perpendicular media to allow use of magnetic materials with higher magnetic anisotropy (Ku) to increase media thermal stability. This paper is an experimental study of ECC media. Our results show that overwrite (OW) of perpendicular media can be improved significantly by the addition of an exchange control layer (ECL), consistent with the original ECC media design proposal. However, such OW improvement can also be achieved with non-ECC media (without ECL) by thickening of the cap magnetic layer. We observe that at similar OW, the non-ECC media can have similar magnetic core width (MCW) to ECC media with even higher thermal decay energy barrier (KuV/kT). The advantage of the ECC media is, instead, media signal-to-noise ratio increase over the non-ECC media. It is also observed that magnetic property and recording performance of the ECC media strongly depend on the magnetic properties and thicknesses of both ECL and cap magnetic layer.