Stacked CoCrPt:SiO/sub 2/ Layers for perpendicular recording media

Perpendicular recording media for high areal density face several requirements such as small grain size, high coercivity, and negative nucleation field. Previous studies on increasing the oxygen concentration in CoCrPt:SiO/sub 2/ media to reduce the grain size indicated that the increase of oxygen flow can lead to undesirable properties such as low coercivity and positive nucleation field. We propose recording media with two or more CoCrPt:Si/sub 2/ layers to obtain optimum microstructure and magnetic properties. In this study, we prepared CoCrPt:SiO/sub 2/ media with two magnetic layers and the increase of oxygen flow rate ratio in the bottom layer, up to 2.3% did not lead to a decrease of coercivity or increase of nucleation field. A high coercivity, negative nucleation field, etc., can be observed. The signal-to-noise ratio (SNR) of the recording media increased up to a flow rate of 2.3%. The results indicate that by optimizing the oxygen composition in the bottom and top layers of stacked CoCrPt:SiO/sub 2/ recording media, recording performance can be enhanced.