CONTROL OF ORIENTATION AND CRYSTALLITE SIZE OF BARIUM FERRITE THIN-FILMS IN SPUTTER-DEPOSITION

Hexagonal barium ferrite thin films were deposited in a facing target sputtering system. Films with random orientation, and c-axis orientati on were obtained by depositing the films on a thermally oxidized silic on wafer and on a c-axis oriented ZnO underlayer, respectively. The fi lm deposited on the thermally oxidized silicon wafer had crystallite s izes as large as 1500 Angstrom, which was increased to about 2000 Angs trom by depositing the film on the substrate with ZnO underlayer. The randomly oriented film had a large coercive force of about 4000 Oe and exhibited almost isotropic properties. In contrast, the c-axis orient ed film deposited on ZnO underlayer had a large perpendicular magnetic anisotropy field above 10 kOe and exhibited an angular dependence of coercivity consistent with a fanning model, although the film had a sm aller coercive force and smaller saturation magnetization. A strong ne gative magnetic interaction operated between the particles in the perp endicular direction of the film. These BaM films had a large dispersio n in coercivity even in the film with excellent c-axis orientation (De lta theta(50) = 1.6 degrees).