Preparation of Ba ferrite films with large saturation magnetization by Xe sputtering and magnetic properties

Ba ferrite films were deposited epitaxially on ZnO underlayer from targets with composition of BaO&middot6.5Fe2O3 using the facing targets sputtering apparatus. The gas mixture of Ar and Xe at 0.18 Pa and O2 at 0.02 Pa was used as the sputtering gas and the dependences of crystallographic and magnetic characteristics on the partial Xe pressure PXe (0.0-0.18 Pa) were investigated. Films deposited at various PXe and at substrate temperature of 600°C were composed of BaM ferrite and spinel crystallites, and the minimum centerline average roughness Ra of 8.9 nm was obtained at PXe of 0.10 Pa and then the saturation magnetization 4πMs of 5.1 kG and perpendicular anisotropy constant Ku(l) of 4.23 × 105 J&middotm-3 were larger than those of bulk BaM ferrite of 4.8 kG and 3.30 × 105 J&middotm-3, respectively. C-axis orientation was observed even for the film deposited at low Ts of 475°C and 4πMs, perpendicular and in-plane coercivity, Hc(⊥) and Hc(), were 4.7 kG, 2.38 and 0.19 kOe, respectively.