A new, purely electrical method for imaging the state of the polarizations in ferroelectric and piezoelectric materials and their crystal anisotropy is proposed. It involves the measurement of point-to-point variations of the nonlinear dielectric constant of a specimen and is termed as scanning nonlinear dielectric microscopy (SNDM). This is the first successful, purely electrical method for observing the ferroelectric polarization distribution without the influence of the screening effect from free charges. Using this higher order nonlinear dielectric microscopy technique, the surface layer of ferroelectrics was successfully evaluated. It is concluded that the SNDM is very useful for observing ferroelectric nanodomain and local crystal anisotropy of dielectric material with subnanometer resolution and also has a high potential as a nanodomain engineering tool.
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