Control of M-H Loop Shape in Perpendicular Recording Media by Ion Implantation

We have investigated the properties of CoCrPt-SiO₂ perpendicular recording media as influenced by Co ion implantation, and have shown that a substantial change of the M-H loop squareness and a control of coercivity (H_c) over a wide range are feasible. Thin films of Ta(5 nm)/Ru(20 nm)/CoCrPt-SiO ₂ (15 nm) were deposited and then subjected to the ion implantation with various acceleration energies, doses, and incident angles. It has been found that the cobalt ion implantation significantly alters the magnetic properties of CoCrPt-SiO ₂. In the case of the near-perpendicular implantation at 60 KV, the M-H loop became much squarer but there was a decrease of coercivity 4300 to 2100 Oe. There was no noticeable decrease of the saturation magnetization by implantation. The reason for the significantly increased squareness by near-perpendicular implantation is mainly attributed to the increase of exchange coupling between the grains by cobalt ion implantation