In-plane hard magnetic BaFe₁₂O₁₉ thin films grown on a-plane Al₂O₃ 11 2 ¯ 0 substrates

Ferrimagnetic barium hexaferrite (BaFe 12 O 19 ) thin films of varying thicknesses were grown on a -plane Al 2 O 3 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 BaFe 12 O 19 film growth and structure. The results indicate that the formation of an α-Fe 2 O 3 ‘bridge layer’ promotes the growth of a BaFe 12 O 19 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 BaFe 12 O 19 10 1 ̅ 0 //α-Fe 2 O 3 11 2 ̅ 0 //Al 2 O 3 11 2 ̅ 0 . As the thickness increases, the fraction of the BaFe 12 O 19 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 BaFe 12 O 19 grains points along the [ 0001 ] easy axis direction.