Impurity effect of carbon on structure and saturation magnetization of Fe-N films

Fe-C-N (C = 0.9-2.5 at%, N = 0-16.5 at%) films have been formed on MgO single-crystal substrates using reactive sputtering. Impurity effect of C atoms on the structure and magnetic moment are discussed. The results can be summarized as follows: (1) In α′-Fe-C-N films, N and C atoms are interstially located along c direction. (2) Substituting N of α′-Fe₁₆N₂ by C, the phase decomposition temperature from α′ to α and γ′ increases with increasing C content. (3) σ_s decreases by substituting N of α′-Fe₁₆N₂ by C. (4) A giant magnetic moment in the Fe-N system does not originate from impurity effect of C atoms.