抄録
The magnetic properties and recording performance of hard/soft-stacked media consisting of a magnetically hard layer (9-10 nm) underneath a very thin soft layer (2 nm) with a large saturation magnetization were investigated. Magnetic energy calculations revealed that reducing the strength of the interfacial exchange coupling between the hard and soft layers reduces the remanence coercivity, Hr. Moreover, an increase in the saturation magnetization of the soft layer <Mssoft> significantly enhances the Hr reduction. It is theoretically predicted that the grain volume of hard (10 nm)/soft (2 nm) stacked media having <Mssoft> of 1000 emu/cm3 could be reduced to about 1/3 that of conventional media whilst maintaining good recording writability and thermal stability. An experimental study of stacked media revealed that the magnetization reversal mechanism changed systematically as a function of the strength of the interfacial exchange coupling, as predicted theoretically. The Hr reduction on adjusting the interfacial coupling reached 22% of that of media consisting of directly coupled hard/soft grains. It was successfully demonstrated that hard/soft-stacked media having thin soft layers with a large <Mssoft> showed better recording writability without degradation of SNmR, recording resolution, or thermal stability.
