Optimization of Soft Layer Uniaxial Anisotropy Gradient in Media for Microwave-Assisted Magnetic Recording

Exchange-coupled composite (ECC), notched, and graded anisotropy recording media were optimized for microwave-assisted magnetic recording at head-medium spacings from 4.5 to 14.5 nm. When the average value of uniaxial anisotropy ( Ku ) in the soft layer was low, notched media gave the best recording performance. As the average soft layer Ku increased, first ECC and then graded anisotropy media became optimal. When the hard layer Ku was high, notched media outperformed graded anisotropy media. However, the performance of graded anisotropy media improved as the hard layer Ku was reduced, and when the hard layer Ku was sufficiently small, graded anisotropy media were preferred.