Effects of alloying and strain on the magnetic properties of Fe$_{16}$N$_2$

TL;DR

This study investigates how alloying and strain influence the electronic structure and magnetic properties of Fe$_{16}$N$_2$, revealing site-specific contributions to anisotropy and potential methods to enhance magnetic performance.

Contribution

It provides a detailed theoretical analysis of doping and strain effects on Fe$_{16}$N$_2$'s magnetic properties using advanced computational methods.

Findings

Doping affects magnetic moments and exchange interactions.

Magnetocrystalline anisotropy energy varies significantly across Fe sites.

Strain and small alloying additions can increase MAE.

Abstract

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 {\emph{GW}} approximations. The {\emph{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. The theoretical Curie temperature in pure {Fe$_{16}$N$_2$} is significantly higher than the measured value, which is attributed 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 MAE by small additions of Co or Ti. MAE also increases under tetragonal strain.