Enhanced ferromagnetism in N-doped BiFeO3: A first-principles prediction

First-principles calculations are used to investigate the ferromagnetism of N-doped BiFeO3 (BFO). It is found that one N atom doped BFO at O site can produce a total magnetic moment of 1 μB compared with the no magnetic moment in the perfect BFO. The magnetic moment originates from the destroyed antiferromagnetic spin arrangement of Fe ions, the spin-polarized N and O atoms. Systematic study of electronic structure further indicated that the magnetism is attributed to the holes in the N-2p, O-2p and Fe-3d states induced by N substitution for O atom. Total energy calculations show that the N impurities tended to ferromagnetic alignment in BFO. Magnetism is also investigated with the appearance of intrinsic defects (Bi and O vacancies) in N-doped BFO, we found that Bi vacancies are beneficial for enhancing the ferromagnetism while O vacancies are the opposite. The enhanced ferromagnetism obtained by N doping indicating a promising way for improving multiferroic properties of BFO.