Structural, electronic and optical properties of BiFeO₃ studied by first-principles

The structural, electronic and optical properties of BiFeO₃ (BFO) were investigated employing the first-principles within generalized gradient approximation (GGA). The magnetic moments were balanced out each other by the two irons spinning oppositely in a cell. The band gap of BFO was found to be 2.5 eV by the electronic structure calculation. Analysis of the density of states indicated that the valence band was consisted with Fe-d and O-p states, and the conduction band was composed of Fe-d and Bi-p states. The dielectric function, absorption, refractive index, extinction coefficient, reflectivity and electron energy loss were calculated for radiation up to 31 eV in order to understand optical properties of BFO. The reasons of the absorption were discussed.