MFM study of the effects of thickness and composition in high recording density CoCrTa/Cr media

Abstract

The effects of differing thickness and Cr concentration of CoCrTa/Cr thin-film media for ultrahigh-density recording were studied with magnetic force microscopy (MFM). Although the remanence-thickness product Brδ increases linearly with magnetic layer thickness δ, the readback signal at high linear recording densities does not change linearly, as expected from the thickness loss factor in the Wallace equation. Increased medium thickness broadens the transition width. Increasing the Cr concentration in CoCrTa films decreases Br, but weakens intergranular exchange coupling and so avoids the bridging between neighboring magnetization transitions and the breaking-up of magnetization patterns recorded at high linear densities. Therefore, the effects of δ and Cr composition must be simultaneously taken into account in the design of ultrahigh-density recording media.