Full-potential calculations of the magnetization of Fe16N2 and Fe4N

Abstract

The magnetization of ${\mathrm{Fe}}_4$N and ${\mathrm{Fe}}_{16}$ ${\mathrm{N}}_2$ has been calculated from first principles, employing the full-potential linearized-augmented-plane-wave method. The calculated magnetization of ${\mathrm{Fe}}_4$N is in fair agreement with experimental results. The differences between calculated and experimental values are at most 10%. The calculated magnetization of ${\mathrm{Fe}}_{16}$ ${\mathrm{N}}_2$, however, is 30% smaller than the huge value of ${\mathrm{\mu }}_0$ ${\mathit{M}}_{\mathrm{sat}}$≃3.2 T reported recently for iron-nitride thin films, which were characterized as single-phase ${\mathrm{Fe}}_{16}$ ${\mathrm{N}}_2$. Based on this result and on a comparison between calculated and experimental hyperfine fields we conclude that the α’ ’-${\mathrm{Fe}}_{16}$ ${\mathrm{N}}_2$ phase cannot be responsible for the ultrahigh magnetization reported for single-phase iron-nitride thin films.