Os‐doped γ‐Fe₂O₃ thin‐film media for perpendicular recording

Abstract

Abstract Since Os‐doped γ‐Fe 2 O 3 sputtered thin film can be added in perpendicular anisotropy by annealing in the magnetic field perpendicular to the film surface, it has potential as a perpendicular magnetic recording media. Herein we examine both a method to dope Os by reactive sputtering and the causes contributing to the induced magnetic anisotropy. Its performance as a perpendicular magnetic disk has yielded the following results. When Os is solidified during the formation of Fe 3 O 4 film by reactive sputtering, reproducible doping is possible. When γ‐Fe 2 O 3 is formed in atmospheric oxidation, the coercive force increases in proportion to the Os doping ( H c ∝ 500 x, x = Os at. %). Magnetic anneal is effective for the γ‐Fe 2 O 3 state, and a large anisotropy can be added when the oxygen partial pressure in the atmosphere is increased. Furthermore, the activation energy for the induced anisotropy was approximately 1.0 eV. The induced anisotropy seems to be related to the vacancies. In the recording reproduction using a thin‐film ring head, the reproduced isolated waveform is dipulse, thereby confirming the recording with a large perpendicular component (dipulse ratio 0.7).