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 Å~25 Å) and gradually increases for further increase of Cr spacer thickness (25 Å~300 Å). The highest signal-to-noise ratio improvement obtained was 5.5 dB for a double magnetic layer film with 25 Å Cr separation, rather than the expected 3 dB for the film with thicker Cr separation. The remanent magnetization δM-curves vs. applied field are utilized to study the magnetic interactions between the two magnetic layers. The results indicate that 25 Å 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