In-plane hard magnetic BaFe12O19 thin films grown on a-plane Al2O3 substrates

Ferrimagnetic barium hexaferrite (BaFe12O19) thin films of varying thicknesses were grown on a-plane Al2O3 11 2 ̅ 0 substrates at elevated temperatures using pulsed laser deposition. X-ray diffraction measurements, Raman spectroscopy, and atomic force microscopy analyses were used to investigate the BaFe12O19 film growth and structure. The results indicate that the formation of an α-Fe2O3 ‘bridge layer’ promotes the growth of a BaFe12O19 phase showing an in-plane uniaxial magnetic anisotropy with an easy-axis of magnetization along the [ 0001 ] hexagonal c-axis direction. The crystallographic relationship between the existing phases is given by BaFe12O19 10 1 ̅ 0 //α-Fe2O3 11 2 ̅ 0 //Al2O3 11 2 ̅ 0 . As the thickness increases, the fraction of the BaFe12O19 phase increases further. This is accompanied by a change in grain morphology turning from a columnar to a more elongated shape, where the short axis of the BaFe12O19 grains points along the [ 0001 ] easy axis direction.