Effect of Composite Designs on Writability and Thermal Stability of Perpendicular Recording Media

The function of two types of magnetic inhomogeneity employed in perpendicular magnetic recording media designs are analyzed. Continuous granular composite (CGC) media have variable lateral exchange coupling (Hex) through the thickness of the magnetic layers, which can reduce coercivity (Hc) and narrow switching field distribution (SFD). Exchange coupled composite (ECC) media have variable crystalline anisotropy field (Hk) and interlayer exchange coupling (J) through the film thickness, which also reduces Hc. Interactions between the Hk, Hex, and J values of combined ECC+CGC media are presented. The optimum anisotropy profile for conventional ECC media is found to be different than previously modeled. A CGC layer included in the ECC media architecture is shown to change the optimal anisotropy profile and interlayer coupling values.