Patterned media with composite structure for writability at high areal recording density

Writability in bit-patterned media (BPM) is a critical issue for high areal densities. In this study, magnetization reversal for multilayer of (Co/Pd) nanodots was investigated using magnetic force microscopy. We observed an increase of more than 15 times in switching field ( H sw ) in BPM over that of continuous films. An exchange coupled structure made of a thin Co layer with in-plane magnetization and high perpendicular anisotropy layer of (Co/Pd) multilayer to reduce the switching field is proposed. When the Co layer is thinner than 2 nm, its magnetization is aligned perpendicular to the film plane due to the exchange coupling with the 15 nm thick (Co/Pd) multilayer. The thin Co layer helps in reducing the H sw of (Co/Pd) by almost 50% and also its distribution by 57% as measured from remanence magnetization.