The electronic structure and magnetic properties of pure and doped Fe${}_{16}$N${}_2$ systems have been studied in the local-density (LDA) and quasiparticle self-consistent $\mathit{GW}$ approximations. The $\mathit{GW}$ magnetic moment of pure Fe${}_{16}$N${}_2$ is somewhat larger compared to LDA but not anomalously large. The effects of doping on magnetic moment and exchange coupling were analyzed using the coherent potential approximation. Our lowest estimate of the Curie temperature in pure Fe${}_{16}$N${}_2$ is significantly higher than the measured value, which we mainly attribute to the quality of available samples and the interpretation of experimental results. We found that different Fe sites contribute very differently to the magnetocrystalline anisotropy energy (MAE), which offers a way to increase the MAE by small site-specific doping of Co or Ti for Fe. The MAE also increases under tetragonal strain.

• Received 9 April 2013

DOI:https://doi.org/10.1103/PhysRevB.88.024404