The electronic structure, magnetism, and dielectric functions of BiFeO3with intrinsic vacancies, including Bi-, Fe-,and O-vacancies(denoted as VFe, VBi, and VO, respectively) are investigated using the first-principles density functional theory plus U calculations. It is revealed that the structural distortions associated with those vacancies impose significant influences on the total density of state and magnetic behaviors. The existence of VBifavors the excitation of the O2pstate into the band gap at 0.4 eV, while the O2pand Fe3dorbitals are co-excited into the band gap around 0.45 eV in VFe.Consequently, a giant net magnetic moment of 1.96 μBis generated in VFe, and a relatively small moment of 0.13 μBis induced in VBi, whereas VOseems magnetically inactive. The giant magnetic moment generated in VFeoriginates from the suppression of the spatially modulated antiferromagnetic spin structure. Furthermore, VFeand VBihave strong influences on dielectric function, and induce some strong peaks to occur in the lower energy level. In contrast, VOhas a small effect.
