Very high-density and low-cost perpendicular magnetic recording media including new layer-structure "U-Mag"

We have fabricated a new layered structure, named "U-mag," for perpendicular magnetic recording media, in terms of stacked films including a very thin (2 nm) ferromagnetic (Co) intermediate layer and lattice spacing control layers. The formed medium having a 100-nm soft magnetic underlayer with high coercivity over 6 kOe and sufficient nucleation field (-1.5 kOe) shows higher signal-to-noise ratio (SNR) than a medium with a conventional Ru underlayer. The detailed microstructures of the U-mag medium were also revealed by a transmission electron microscope with an energy dispersive spectrometer. A double Co intermediate layer gave a significant improvement in the SNR compared to a single Co layer.