Nonlinear dielectric imaging

Moreover the magnitude of em = e222 is zero in the a-domain, because bto belongs to tetragonal system at room temperature. Thus, we can easily distinguish the type of the domains. 

These images of the film were taken from a relatively large area. Therefore, we also tried to observe very small domains in the same pzt film on sto substrate. The results are shown 

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Nonlinear dielectric imaging with sub- nanometer resolution... 

A higher order nonlinear dielectric microscopy technique with higher lateral and depth resolution than conventional nonlinear dielectric imaging is investigated. The technique is demonstrated to be very useful for observing surface layers of the order of unit cell thickness on ferroelectric materials. 

With this background, we have proposed and developed a new purely electrical method for imaging the state of the polarizations in ferroelectric and piezoelectric material and their crystal anisotropy. It involves the measurement of point-to-point variations of the nonlinear dielectric constant of a specimen and is termed scanning nonlinear dielectric microscopy (sndm) [1-7]. This is the first successful purely electrical method for observing the ferroelectric polarization distribution without the influence of the screening effect from free charges. To date, the resolution of this microscope has been improved down to the subnanometer order. 

Here we describe the theory for detecting polarization and the technique for nonlinear dielectric response and report the results of the imaging of the ferroelectric domains in single crystals and thin films using sndm. Especially in a measurement of pzt thin film, it was confirmed that the resolution was sub-nanometer order. We also describe the theoretical res-... 

To date, a number of chemically selective near-field imaging methods have been demonstrated. Near-field contrast mechanisms that rely on electronic spectroscopy (UV-visible absorption and fluorescence),204 vibrational spectroscopy (IR absorption and Raman spectroscopies), dielectric spectroscopy (microwave dispersion), and nonlinear spectroscopy (second harmonic generation) have all been demonstrated at length scales well below the diffraction limit of light. 

Another frequently reported high-resolution tool for observing ferroelectric domains is piezoelectric response imaging using sfm [8,9], From the viewpoint of resolution for ferroelectric domains, sndm will surpass the piezo-response imaging because sndm measures the nonlinear response of a dielectric material which is proportional to the square of the electric field,... 

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