Potential of metallic glass thin films as a soft magnetic underlayer for L1₀ FePt-based recording media

We report on the use of metallic glass (FeHfNbYB) thin film as a soft magnetic underlayer for the fabrication of L1₀ FePt-based bit patterned recording media (BPM). Preferred oriented phase of L1₀ (111) FePt is obtained either by depositing it in situ on a heated soft magnetic metallic glass/SiO₂Si or at room temperature (FePt/metallic glass/SiO₂Si) followed by annealing at 400°C-450°C for 20 min. Fabrication of recoding bits of size ∼2μm to 20 nm is demonstrated using electron beam lithography. Magnetic measurements on ∼500nm bit patterns show a narrow switching field (SF) distribution with SF of ∼3kOe. The ability to read/write this BPM is demonstrated with a commercial head in perpendicular geometry in a static tester. Results strongly suggest that the soft magnetic metallic glass thin films can solve the problem of writability in high anisotropy L1₀ FePt-based recording media.