Enhancement of exchange coupling for antiferromagnetically coupled media

Antiferromagnetically coupled (AFC) media with CoPt or Co interlayers inserted between a Ru layer and CoCrPtB magnetic layers were prepared in order to enhance the exchange coupling and the thermal stability. The exchange coupling field H-ex increased from 0.6 to 4.2 kOe by increasing the thickness of the Co interlayer from 0 to 1 nm. The coupling energy J increases with increasing thickness of the interlayer. The coupling energy J of the AFC media with the interlayer are ten times larger (for 1-nm-thick Co interlayer) and five times larger (for 1-nm-thick CoPt interlayer) than that of the medium without the interlayer. Thermal stability factor KuV/k(B)T for the media with 1-nm-thick Co and 1-nm-thick CoPt interlayers are about 10% larger than that for the medium without the interlayer. The results suggest that the enhancement of the exchange coupling energy induces the increasing of KuV/k(B)T in the AFC media. (C) 2002 American Institute of Physics.