Abstract
We compared the electric fields required for the ferroelectric domain reversal between the conventional congruent LiNbO_3 crystal and stoichiometric one which was grown by the novel double crucible Czochralski method equipped with an automatic powder supply system. It turned out that the electric field for domain switching in the stoichiometric crystal was 3〜4 kV/mm. This value was much smaller (about one fifth) than that of the congruent crystal. The spontaneous polarization, Ps, didn't depend on the nonstoichiometry. We checked also the dependence of this domain switching nature on the proton density in the crystals. It was confirmed that the proton concentration had no influnece on the electric field for domain switching, internal field, and Ps. These results are suggesting that the stoichiometric LiNbO_3 crystal has a high controllability in ferroelectric domain switching and has a high excellence in the QPM device fabrication.
