Investigation of structure and magnetic properties of the as-deposited and post-annealed iron nitride films by reactive facing-target sputtering

Structure and magnetic properties of the as-deposited and post-annealed iron nitride films have been investigated systematically. A series of phases containing α-Fe, ?-Fe₃N, ξ-Fe₂N and γ″-FeN were obtained as nitrogen flow rate (FN₂) increases from 0.5 to 30 sccm. An increase of the nitrogen concentration in the as-deposited films could be concluded from the phase transition with the increasing FN₂. After being annealed, some of the iron nitride phases are decomposed and γ′-Fe₄N appears in the films. The magnetic characteristics are dependent on FN₂, which can be ascribed to the facts that the nitrogen in the films turns the valence states of Fe into Fe⁺ or Fe^dipole with high magnetic momentum or ever H-like bond Fe^+/dipole with low magnetic momentum based on the bond-band-barrier correlation mechanism.