Effect of Carbon Overcoat on Heat-Assisted Magnetic Recording Performance

Heat-assisted magnetic recording (HAMR) is a promising approach for enabling large increases in the magnetic data storage density. Amorphous carbon is the principal overcoat material of thin-film disks and magnetic heads in the HAMR systems. In this paper, we investigated the recording performance of media with a chemical vapor deposition (CVD) carbon overcoat (COC) and a sputtered COC. We observed that the carbon type has a significant impact on the HAMR recording performance and the heat absorption. Tunneling current atomic force microscopy analysis results show higher surface roughness and peak current in the disk with the sputtered carbon. Track profile and magnetic signal measurement results indicate 90% of the optimized laser current is not enough to fully write the disk with the CVD carbon, while the tracks on the sputtered carbon disk can be written using the same laser current. The difference in the two types of COC can be attributed to the difference in the carbon bonding structure, the optical and electrical properties, the roughness, and the heat absorption behavior.