First-principles calculations of multiferroic properties of crystallographic shear plane in BiFeO₃

Abstract

Multiferroic properties of crystallographic shear (CS) plane in BiFeO₃ are calculated using first-principles calculations. We find that the polarization and the magnetic moment are spontaneously rotated by 109 degrees through CS plane, while those in BiFeO₃ bulk are uniform. The rotation of the polarization shows the transition involving its continuous rotation and discontinuous head-to-head type reversal, which is generally unstable in perfect crystal. These multiferroic properties are caused by edge-sharing of oxygen octahedra and localization of hole which emerges by nonstoichiometry of CS plane.