Growth,magnetic properties and the effect of cobalt addition in metal-organic chemical vapour deposited (MOCVD) gamma iron oxide thin films for magnetic recording applications

The present study aims at investigating MOCVD technique for the deposition of magnetic oxide thin films using volatile metal-organic compounds as source material. A three-step scheme has been described to form γ-Fe₂O₃ phase starting from α-Fe₂O₃ films as-deposited in optically heated atmospheric cold wall CVD reactor. Growth of γ-Fe₂O₃ in a two-step process has been performed by depositing Fe₃O₄ phase directly by resistively heated low-pressure CVD (LPCVD) technique. Role of substrate temperature in controlling the oxidation leading to direct formation of metastable γ-Fe₂O₃ phase (single-step scheme) by atmospheric CVD technique has been described. A new mode of introduction of cobalt in the film, namely heterogeneous dispersion of cobalt in the γ-Fe₂O₃ matrix, has also been described. Crystallographic structure, microstructure and magnetic properties of the films have been studied in detail. Biaxial vector coil and high-temperature magnetic studies were carried out for determining the nature of anisotropy in the γ-Fe₂O₃ film. Growth of γ-Fe₂O₃ films in different schemes have been discussed from the studies of growth kinetics in a cold-and hot-wall-type reactor chambers.