Crystallographic phases and magnetic properties of iron nitride films

Iron nitride films, including single phase films of α-FeN (expanded bcc Fe), γ′-Fe4N, ε-Fe3−xN (0≤x≤1), and γ″-FeN, were sputtered onto AlN buffered glass substrates. It was found possible to control the phases in the films merely by changing the nitrogen partial pressure during deposition. The magnetization decreased with increased nitrogen concentration and dropped to zero when the N:Fe ratio was above 0.5. The experimental results, along with spin polarized band calculations, have been used to discuss and analyze the magnetic properties of iron nitrides. It has been demonstrated that in addition to influencing the lattice constant of the various iron nitrides, the nearest N atoms have a significant influence on the exchange splitting of the Fe atoms. Due to the hybridization of Fe-3d and N-2p states, the magnetic moment of Fe atoms decreases with an increase in the number of nearest neighbor nitrogen atoms. •Single phase γ′-Fe4N, ε-Fe3−xN, and γ″-FeN films were obtained using dc sputtering.•The phases in iron nitride films can be controlled by the nitrogen partial pressure.•The nearest N neighbors have a significant influence on the exchange splitting of Fe.