DIRECT DEPOSITION OF HIGHLY COERCIVE GAMMA-IRON OXIDE THIN-FILMS FOR MAGNETIC RECORDING

Direct preparation of high coercivity gamma iron oxide (gamma-Fe2O3 thin films by chemical vapor pyrolysis techniques have been described. Films deposited at temperatures above 500-degrees-C have the gamma- and those deposited below 500-degrees-C have the alpha-Fe2O3 phase. Gas phase reactions leading to oxygen deficiency in the vicinity of substrate and consequently controlled in situ oxidation of Fe3O4 appear responsible for direct growth of the gamma-Fe2O3 film. Magnetic properties of these films are optimized by adding cobalt. High coercivity values of 3 kOe for directly deposited gamma-Fe2O3 films containing 6 at. % of cobalt are obtained along with reasonable values of remanence almost-equal-to 2.8 kG and squareness ratio of 0.83. These values are considerably superior for magnetic recording in comparison to those for gamma-Fe2O3 films obtained by reduction and reoxidation of alpha-Fe2O3 films.