Compositional and magnetic properties of iron nitride thin films

The compositional and magnetic properties of iron-nitride thin films deposited by dc reactive magnetron sputtering under various nitrogen partial pressure conditions have been investigated by x-ray diffraction, Mössbauer and Auger electron spectroscopy as well as magnetic measurements. The x-ray diffraction patterns indicate a mixed phase composition. 57Fe Mössbauer spectroscopy shows that part of the nitrogen atoms are randomly distributed on interstitial sites with the formation of nonstoichiometric compounds. The excessive width of the Mössbauer lines indicates the degree of disorder of the different iron nitride precipitates. The nitrogen concentration as a function of depth is obtained by sputter-etched Auger electron spectroscopy. Furthermore, the ferromagnetic films show moderate saturation magnetization and coercivities at room temperature as compared with pure iron thin films.