Mariana Rodica Munteanu

Influence of oxide on the structural and magnetic properties of CoPt alloy

Perpendicular recording media consisting of isolated CoPt magnetic grains separated with a nonmagnetic oxide grain boundary can be prepared by sputtering a Ru interlayer and then cosputtering CoPt with an oxide material, with low adatom mobility. The oxide material moves into the grain boundaries and isolates the magnetic grains. An increase in the oxide volume fraction in the magnetic layer does not affect the saturation magnetization but significantly reduces the magnetocrystalline anisotropy of magnetic grains. This may impose a limit on the areal density capability of this media design since media with smaller grains will require a larger oxide volume fraction that will reduce magnetocrystalline anisotropy of the CoPt based magnetic grains.

Different designs and limits of longitudinal magnetic recording media

Combining antiferromagnetically coupled (AFC) and laminated media (LM), we were able to incorporate the stability of AFC media with the signal-to-noise ratio (SNR) of LM. This improvement is directly related to the decrease of the demagnetization field which is calculated to be up to 50% of the LM case for some configurations of AFC+LM that were experimentally realized. The stabilization layer also increases the magnetic energy barrier of the recording layers in the AFC+LM structure, which further improves the stability of this media. An improvement of ∼1 dB in SNR was observed in AFC+LM in comparison to single layer media.