Single Cation Contributions to the Polarization in GaFeO3 (Mars 2014)

The electric polarization in the multiferroic GaFeO₃ system is investigated from its electronic structure using first principles methods and the modern theory of polarization. The polarization is analyzed in a local point of view to identify the cations that have the main contribution to the polarization of the cell. This is done by carefully following the structural transformation of the oxygen environment of each cation on a path connecting a centrosymmetric structure to the polar one. Nominal and Born effective charges along the path are considered but both kinds of charges lead to similar conclusions. It is shown that the Ga sites have a much larger contribution to the polarization than the magnetic Fe ones.