Abstract
Barium ferrite films were prepared by r.f. diode sputtering on AlN underlayers, whose influence on the films’ c-axis orientation and magnetic properties was investigated. Hexagonal AlN underlayers with thicknesses of around 30-100 nm were deposited at room temperature. On the underlayers with a thickness of 30 nm, barium ferrite films with a thickness of 50 nm were deposited at room temperature. As the deposited barium ferrite films were not crystallized, they were post-annealed at temperatures between 600 °C and 900 °C for 5h in air. When the films were annealed at 800 °C, superior perpendiculaly oriented films were obtained, exhibiting a saturation magnetization Ms of 203 emu/cm3, a perpendicular coercivity Hc⊥ of 5.5 kOe, a squareness ratio Sq⊥/Sq// of 2.7, and a coercivity ratio Hc⊥/Hc// of 1.6. This excellent uniaxial c-axis orientation lying perpendicular to the film surface may be presumed to result from the effect of the AlN underlayer.
