Nitrogen concentration induced spin disorder in ε-iron nitrides

Highlights: • The T_C of ε-Fe_3−xN can be expressed as $T_C=\text{A}[{(1-x)}^2{J}_{\text{Fe}\left(2\right)-\text{Fe}\left(2\right)}+2x(1-x)J_{\text{Fe}\left(2\right)-\text{Fe}\left(3\right)}+x^2{J}_{\text{Fe}\left(3\right)-\text{Fe}\left(3\right)}]$. • Contribution of magnetic scattering to the resistivity of ε-Fe_3−xN is identified. • A negative MR described by the Khosla-Fischer model is observed in ε-Fe_3−xN. The magnetic and transport properties of ε-Fe_3−xN (0 ≤ x ≤ 1) films were systematically characterized to identify the correlation among the nitrogen concentration x, magnetic structure, and electrical transport properties. It was found that increasing the nitrogen concentration x of ε-Fe_3−xN not only resulted in a successive decrease in magnetization and Curie temperature, but also led to the contribution of magnetic scattering to the resistivity and magnetoresistance. All these experimental phenomena can be attributed to the distinctive exchange interaction in ε-Fe_3−xN, which depends on the concentration and distribution of nitrogen atoms and causes the emergence of localized spin disorder. We believe this work would provide a new insight into the relationship between the magnetic and transport properties of iron nitrides.