Fe-Ta-C soft underlayer for double-layered perpendicular recording media

We report the investigation of microstructure, magnetic domain structure, and magnetic properties of Fe-Ta-C thin films for the application of soft underlayer (SUL) of perpendicular magnetic recording (PMR) media. As-deposited Fe80 Ta8 C12 film showed an amorphous structure with low saturation magnetization (MS ∼600 emucc) and high coercivity (HC ∼18 Oe), while the optimally annealed (≤500 °C) films exhibited high value of MS (∼1350 emucc) and low HC (∼0.3 Oe). The magnetic domain structures and their correlation with the microstructures suggest that the refinement of the average α-Fe grain size below 15 nm and the magnetic properties of the intergranular residual amorphous matrix are very important in obtaining improved soft magnetic properties. These results indicate that Fe-Ta-C films would be a suitable candidate for SUL of FePt PMR media, for which the annealing for L 10 ordering is essential.