Ion implantation induced modification of structural and magnetic properties of perpendicular media

Abstract

This study reports the effects of implanting various doses of boron (11B + ) and argon (40Ar + ) ions into the recording layer and the soft underlayer of CoCrPt–SiO 2 -based perpendicular recording media. Implantation of a lower dose of boron ions (10 11 ions cm −2 ) in the recording layer was found to reduce the out-of-plane coercivity, whereas no changes in the coercivity were observed when they were implanted into the soft underlayer. In the case of argon ions, lower dose implantation did not show any changes in the coercivity, irrespective of the implanted layer. However, higher dose implantations (10 16 ions cm −2 ) of all the species were found to cause a reduction in coercivity, irrespective of the implanted layer. The reduction in coercivity was more significant when the ions were implanted in the recording layer compared with the case of implantation in the soft underlayer. X-ray diffraction (XRD) results on samples where argon was implanted in the recording layer showed a strong shift in the position of Co (0 0 .2) peaks, indicating an increase in the ‘ c ’ parameter. The shift is explained, on the basis of x-ray photoelectron spectroscopy, to be arising from intra-layer mixing at the CoCrPt–SiO 2 /Ru interface. Magnetic force microscopy images indicated an increase in domain size arising from the ion implantation.