Physical origin of limits in the performance of thin-film longitudinal recording media

The application of thin-film media for Winchester-type rigid disk recording is considered. The inherent close contact between the magnetic particles in the film introduces strong exchange coupling between them in addition to the magnetostatic interaction generally seen in the particulate-binder-type media. The coupling causes the formulation of an intrinsic magnetic cluster that has a dimension much larger than the individual magnetic crystallites. The exchange-coupling-induced magnetic cluster becomes the basic unit of magnetization reversal in the film under recording, and hence it is believed to cause noise and increase bit shift in the media. It is shown that if a proper interparticle separation is created in the film, the exchange-coupling effect can be reduced or eliminated, so the resulting film will have the low media noise and bit shift required for high-performance-drive applications