Scanning Nonlinear Dielectric Microscope (SNDM) is the method for observing ferroelectric polarization distribution, and now, its resolution has become to the sub-nanometer order. Up to now, we have studied high-density ferroelectric data storage using this microscope. In this study, we selected stoichiometric and congruent LiTaO_3 single crystals as ferroelectric recording media. At first, using stoichiometric LiTaO_3 (SLT), we studied polarization inversion characteristics in detail, and as a result, we achieved forming small inverted domain with the radius of 6 nm. And we also studied the retention of inverted domain. Next, using congruent LiTaO_3 (CLT), we achieved high-density data storage in excess of 1 Tbit/inch^2.
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