Microscopic origin of the giant ferroelectric polarization in tetragonal-like BiFeO(3)

Phys Rev Lett. 2011 Sep 30;107(14):147602. doi: 10.1103/PhysRevLett.107.147602. Epub 2011 Sep 29.


We report direct experimental evidence for a room-temperature, ∼130 μC/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.