Magnetic Properties of Epitaxial Barium Hexaferrite (0001) Thin Films Deposited by Radio Frequency Magnetron Sputtering

We report the growth of barium hexaferrite (BaM) (0001) epitaxial thin films, deposited on α-Al
₂
O
₃
(0001) substrate by radio frequency magnetron sputtering. We found that the ratio of barium to iron in the films was reduced from that of the stoichiometric target. Although the saturation magnetization does not show clear thickness dependence at all, the magnetic anisotropy shows significant thickness dependence due to large surface/interface anisotropy. Taking account of charge neutrality in the BaM accompanying the Ba-rich composition, introducing T-blocks into BaM structure can reasonably explain the experimentally observed reductions in the saturation magnetization and anisotropy energy.