Enhancement of multiferroic in BiFeO3 by Co doping

Abstract

The effects of Co doping on the structure, magnetic and the ferroelectric properties of BiFeO3 were predicted through ab initio calculation based on density functional theory (DFT), in conjunction with experimental verification. The calculated structure of BiFe0.83Co0.17O3 belongs to rhombohedral R3c, which matched well with that obtained experimentally. The calculations revealed that the magnetic properties of BiFeO3 can be enhanced significantly by Co-doping at B-site, and the net magnetic moment of unit cell was evaluated to be 0.93μB for BiFe0.83Co0.17O3. The enhanced magnetic moments should be ascribed to the superexchange interaction of Fe3+–O2−–Co3+. By using the Berry-phase method, the ferroelectric polarization was calculated to be 108μC/cm2, which is larger than that in pure BiFeO3 (93μC/cm2). The observed weak ferromagnetism and ferroelectric nature at room temperature indicates the multiferroic nature of BiFe0.8Co0.2O3 sample, whose magnetoelectric coupling was verified to be 4.82% in BiFe0.8Co0.2O3 estimated by the change of dielectric constant with external magnetic field. These results may shed some light on the controlling and tuning of the multiferroic properties of BiFeO3.