Recording Characteristics and Durability of Fe-Co-O/Fe-Co Double-Layered Perpendicular Magnetic Recording Medium

In order to enhance the perpendicular magnetic recording characteristics of an Fe-Co-O medium with a large perpendicular anisotropy, an Fe-Co underlayer with a coercive force of about 100 Oe was investigated. The voltage reproduced from the Fe-Co-O/Fe-Co double-layered medium with the most suitable film thickness is five times as large as that for a single-layered medium. However, an Fe-Co-O/Ni-Fe double-layered medium, the underlayer of which has a higher permeability, did not show such great improvement in reproduced voltage. These results suggest that the effect of the Fe-Co underlayer is different from the decrease of demagnetization field caused by the Ni-Fe layer in a Co-Cr/Ni-Fe double-layered medium. It was also verified that Fe-Co-O/Fe-Co double-layered flexible disks have a high wear resistance, with a lifetime of more than 10 million passes without a protection layer, because of the higher stiffness and stronger adhesive force between the Fe-Co layer and the polyimide substrate.