Crystal structures and magnetic properties of Fe-N thin films deposited by dc magnetron sputtering

摘要

Fe-N thin films were deposited on glass substrates by dc magnetron sputtering under various Ar/N_2 discharge conditions. Crystal structures and elemental compositions of the films were characterized by X-ray diffraction and X-ray photoelectron spectroscopy. Magnetic properties of the films were measured using a superconducting quantum interference device magnetometer. Films deposited at different N_2/(Ar+N_2) flow ratios were found to have different crystal structures and different nitrogen contents. When the flow ratios were 60%, 50%, and 30%, a nonmagnetic single-phase FeN was formed in the films. At the flow ratio of 10%, two crystal phases of γ′-Fe_4N and ε-Fe_3N were detected. When the flow ratio reduced to 5%, a mixture of α-Fe, ?-Fe_3N, FeN_(0.056), and α″-Fe_(16)N_2 phases was obtained. The value of saturation magnetization for the mixture was found to be larger than that of pure Fe.