Computer simulation of granular perpendicular recording media with dispersions of grain size and grain separation

Micro-magnetic simulation showed the possibility of 300-500 Gbit/in² recording using a granular perpendicular recording medium with large grain separation (LGS medium). Among granular media parameters, a smaller grain size and a larger spacing between grains along with a higher saturation magnetization of grains and perpendicular anisotropy energy of grains are necessary to obtain sufficient values of signal to noise ratio S/N and thermal stability. However, there are some ambiguities in values of S/N and DC medium noise N_DC because the simulation was based on uniform grain size and separation model. In this study, values of S/N and N_DC in the LGS media with dispersions of grain size and separation have been analyzed using modified Voronoi lattice. An array of polygonal prism grains with perfect mirror image for soft underlayer (SUL) was used to simulate a section of a perpendicular recording medium.