Electrical polarization switching in bulk single-crystal GaFeO3

The electrical polarization switching on a stoichiometric $\mathrm{GaFe}{\mathrm{O}}_{3}$ single crystal was measured, and a model of atomic displacements responsible for the polarization reverse was proposed. The widely adapted mechanism of polarization switching in $\mathrm{GaFe}{\mathrm{O}}_{3}$ can be applied to stoichiometric, perfectly ordered crystals. However, the grown single crystals, as well as thin films of Ga-Fe-O, show pronounced atomic disorder. Using piezoresponse force microscopy, the electrical polarization switching on a crystal surface perpendicular to the electrical polarization direction was demonstrated. Atomic disorder in the crystal was measured by x-ray diffraction and M\"ossbauer spectroscopy. These measurements were supported by ab initio calculations. Using analysis of atomic disorder and electronic structure calculations, the energies of defects of cations in foreign cationic sites were estimated. The energies of the polarization switch were estimated, confirming the proposed mechanism of polarization switching in $\mathrm{GaFe}{\mathrm{O}}_{3}$ single crystals.