Growth of highly textured barium ferrite thin films on sapphire and their magnetic properties

Barium ferrite thin films were spin-coated on sapphire (00l) faces. Ethylene-diamine-tetra-acetic acid (EDTA) was used to chelate metal ions. The conditions to obtain highly textured films were expanded by using EDTA, where the pH values of the solutions varied from 3 up to 9 and the molar ratio of EDTA to metal ions changed from 1.0 up to 1.5. The grains showed that the c-axis aligned normal to the film plane and the [110] direction of sapphire was parallel to the [100] direction of the film. The film showed uniaxial magnetic anisotropy with the coercivity field of 21.5 kA/m along the out-of-plane direction and very small hysteresis in the in-plane direction. The coercivity was likely to be controlled by wall nucleation according to the shape of the curves of the coercivity forces versus the maximum applied field.

► Highly textured barium ferrite thin films were obtained by sol–gel methods. ► Films have faceted grains. ► Processing conditions are much extended.