Magnetoplumbite-type Ba ferrite (BaM) layers were deposited on ZnO (002) and Pt (111) underlayers by using a facing-targets sputtering apparatus in a gas mixture of Ar, Xe, and O
2 at various substrate temperatures
Ts. A Ba ferrite layer as-deposited on a ZnO underlayer at
Ts values above 475°C and one as-deposited on a Pt (
mmm) under-layer at
Ts values above 500°C revealed clear
c-axis oientation. The saturation magnetization 4π
Ms was 5.1 kG and 4.0 kG for ZnO and Pt underlayers, respectively. Both underlayers exhibited high perpendicular coercivity
Hc⊥ and low in-plane coercivity
Hc// of about 2.4 and 0.2 kOe, respectively. A Ba ferrite layer deposited at a relatively low
Ts of 300°C and annealed at 800°C in air also revealed excellent
c-axis orientation and exhibited a relatively low perpendicular coercivity
Hc⊥ of 0.6 kOe. A clear di-pulse was observed for the isolated wave form of a BaM/Pt film as-deposited at
Ts of 600°C owing to the perfect perpendicular magnetization orientation, and a relatively high linear recording density
D50 of 123 kFRPI was achieved.
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