First principles study of the electric polarization and of its switching in the multiferroic GaFeO3 system

The electric polarization in the multiferroic GaFeO3 system is determined from its electronic structure using first principles methods and the modern theory of polarization. By carefully following the electric polarization on a path connecting the polar and centrosymmetric structures, it is found to be - 25 μC cm-2, which is ten times larger than a previous estimation given in the literature a few years ago and two times smaller than the value obtained in a recent similar study. The switching of this electric polarization through a centrosymmetric structure is discussed in terms of the total energy barrier. It is exhibited that such a switching is particularly difficult to achieve in relation to the tetrahedral environment of half of the Ga atoms. The switching via domain wall motion is also discussed. (paper)