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 L1(0) FePt-based bit patterned recording media (BPM). Preferred oriented phase of L1(0) (111) FePt is obtained either by depositing it in situ on a heated soft magnetic metallic glass/SiO2/Si or at room temperature (FePt/metallic glass/SiO2/Si) followed by annealing at 400 degrees C-450 degrees C for 20 min. Fabrication of recoding bits of size similar to 2 mu m to 20 nm is demonstrated using electron beam lithography. Magnetic measurements on similar to 500 nm bit patterns show a narrow switching field (SF) distribution with SF of similar to 3 kOe. 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 L1(0) FePt-based recording media.