Effects of inter-layer magnetic interactions in multilayered CoCrTa/Cr thin film media

The magnetic properties and media noise of double-magnetic-layer longitudinal CoCrTa/Cr thin-film media were investigated as a function of the Cr separation layer thickness. It is found that the media noise power decreases rapidly for initial increase of Cr separation layer thickness (10 AA approximately 25 AA) and gradually increases for further increase of Cr spacer thickness (25 AA approximately 300 AA). The highest signal-to-noise ratio improvement obtained was 5.5 dB for a double magnetic layer film with 25 AA Cr separation, rather than the expected 3 dB for the film with thicker Cr separation. The remanent magnetization delta M-curves vs. applied field are utilized to study the magnetic interactions between the two magnetic layers. The results indicate that 25 AA Cr separation layer is adequate to decouple the two magnetic layers from exchange coupling, and the magnetostatic interactions between two magnetic layers can alter the effects of the magnetic interactions inside the magnetic layers so as to further reduce the media noise.>