Oxygen pressure dependence of laser deposited barium ferrite films on LLC(111)

Hexagonal Barium Ferrite thin films with perpendicular anisotropy were successfully fabricated on the (111) surface of large lattice constant (LLC) garnet substrates using pulsed laser deposition. Oxygen pressure plays a crucial role in determining film growth characteristics. The film grown at 50 mTorr oxygen pressure has a clear hexagonal structure but is very weakly crystallized due to the lack of oxygen. Increasing the oxygen pressure enhances both crystallization and the in-plane c-axis oriented crystal growth, hence it reduces the perpendicular anisotropy. The optimum pressure is about 180 mTorr which gives a crystallized film with predominantly perpendicular c-axis orientation. The sensitive dependence of film structure on processing gas pressure shown in this work is important in controlling film properties such as anisotropy and grain size for different applications.