Cobalt ferrite thin films were deposited on TbFeCo(10 nm)/Si(100) and Si(100) substrates at a substrate temperature of 350 ℃ by RF magnetron sputtering. The heat treated films were analyzed by Vibrating Sample Magnetometer (VSM) and X-Ray Photoelectron Spectroscopy (XPS). Results showed that all films had high coercivity and perpendicular anisotropy especially for the films deposited on TbFeCo underlayer. TbFeCo underlayers increase the coercivity, magnetization and remanence ratio of CoFe2O4 films, films on TbFeCo underlayer had coercivity and magnetization as high as 832×103 A·m-1 and 450×103 A·m-1, and its romance ratio reaches 0.9, which was related to the Tb3+ diffusion from the underlayer into the film.
