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 (SIA) on the magnetic anisotropy energy (MAE) of 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 influences the dumbbell structure and the orbital distortion induced by the first nearest-neighbor Fe atoms, thereby altering the contributions of the spin-orbit coupling (SOC) matrix elements, which leads to an increase in the MAE of the crystal. 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.