The effects of ZnO underlayer on microstructural and magnetic properties of BaFe₁₂O₁₉ thin films

Barium ferrite films have been grown by pulsed laser deposition on oxidized Si (100) with and without ZnO buffer layers. The films grown directly on SiO2/Si exhibit a granular structure with two easy axes (in-plane and perpendicular) and strong magnetic coupling. It was found that a ZnO underlayer promotes the orientation of the c-axis perpendicular to the film plane. Additionally, good separation between the grains and a low exchange coupling can be achieved in BaFe12O19/ZnO/SiO2/Si films. Grain isolation and magnetic de-coupling are believed to be caused by the interdiffusion between the film and the ZnO buffer layer, which gives birth to a new non-magnetic phase (ZnFe2O4).