| The key to increasing the areal recording density while maintaining high signal to noise ratio in perpendicular recording is to increase the sharpness of the transition between each bit in a media. In this thesis, two main approaches were attempted to achieve sharp transitions. Firstly, a microstructural study on a commercial perpendicular recording media using analytical TEM techniques diagnosed for the possible causes of broader transitions. It was found that the topology distribution may be one of causes of the large switching field distribution in small grain media. Evidence of random exchange coupling was also observed. Secondly, we changed the media layer structure by replacing part of the conventional Ru intermediate layer with a soft crystalline intermediate layer in order to increase the head field gradient. With the requirements of: (1) hcp (00.2) texture, (2) dome morphology, and (3) soft magnetic properties, practical prototypes were devised and fabricated consisting of a soft magnetic CoPt/CoIr composite design, granular Co-7%Ir--oxide, continuous Co-7%Ir design. We experimentally demonstrated the feasibility of fabricating such designs meeting all the requirements by optimizing the process parameters. Both finite element method and micromagnetic simulation studies proved that a contiguous soft intermediate layer increases the head field gradient. Micromagnetic study further demonstrated that a granular soft intermediate layer improves the head field gradient more than a continuous soft intermediate layer can do. |
