First-principles study of the changes in magnetic anisotropy energy of bcc-Fe under irradiation conditions.

This study uses first-principles calculations to investigate the effect of self-interstitial atoms (SIAs) on the magnetic anisotropy energy (MAE) of body-centered cubic (bcc)-Fe. The results demonstrate that SIA significantly enhances the MAE in bcc-Fe, with a more pronounced effect when the SIA is Mn. The origin of MAE is discussed by combining second-order perturbation theory and electronic structure analysis. SIA increases the spin-orbit coupling matrix element contribution to the MAE of crystals by affecting the dumbbell structure and the first nearest-neighbor Fe atom induced orbital distortion. Additionally, the segregation of solute atoms near the SIA can reduce the MAE. These findings provide insights into the relationship between SIA and magnetic properties and establish a theoretical foundation for further studies on the effects of irradiation on material magnetic properties.