Effects of grain size dispersion on noise in longitudinal thin film media

The effect of grain size dispersion on medium noise in longitudinal thin film recording media is studied by micromagnetic modeling. A previous micromagnetic model has been extended for modeling films with grain size variation. It is found that for the typical thin film media, moderate grain size dispersion in the film does not affect the media noise at low recording densities. At high recording densities, when adjacent transition boundaries percolate, the film with grain size dispersion exhibits a less degree of superlinear noise enhancement than the film with identical size grains. It is concluded that for films with medium noise dominated by magnetic interactions, moderate grain size dispersion slightly suppresses the collective magnetization processes at high recording densities, thereby, reducing medium noise.