A Ba Ferrite Disk Deposited at Low Temperature and Its Read/Write Characteristics

Abstract

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 O2 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 4πMs 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.