Noise of interacting transitions in thin film recording media

The noise of interacting di-bit transition pairs in thin-film longitudinal recording media is studied via computer simulations. It is shown that the intergranular exchange coupling yields large-scale irregular transition boundaries, and thereby large transition noise. At small bit intervals, the magnetostatic interaction field that has resulted from such a noisy transition significantly enhances the noise of a later adjacent transition. Such a mechanism results in a supralinear increase of the integrated noise at high recording densities. The noise increase includes the increases of both position jitter and transition length fluctuations. For films with no intergranular exchange coupling, the transition boundary exhibits narrow finger structures and only a very small supralinear increase of the integrated noise results at small bit intervals. Noise correlations between the two transitions in the di-bit pairs are analyzed for the exchange coupled films