Optimization of granular double-layer perpendicular media

Optimized two types of granular, double-layer perpendicular recording media based on CoCrPtB and CoCrPtO alloy systems focusing mainly on signal-to-noise ratio (SNR) and thermal stability characteristics of the media. For the soft underlayer (SUL) portion of this study we compared NiFe, FeTaC, and FeAlSi films with and without lamination. Lamination of the SUL films resulted in marginal SNR improvement but was not effective in inhibiting the presence of magnetization domains. The CoCrPtB based media was found to have significantly lower noise than CoCrPtO, but its thermally stability is greatly compromised. On the other hand, the CoCrPtO media displayed negative nucleation fields and stable magnetization states even at DC-erased conditions.