Observation of Nanoscale Ferroelectric Domains Using Super-Higher-Order Nonlinear Dielectric Microscopy
Scanning nonlinear dielectric microscopy is a powerful technique for measuring the domain structure of ferroelectrics. We observed congruent LiTaO 3 and found the marked enhancement of nonlinear dielectric "constants" when the applied tip--sample voltage exceeded a particular threshold val...
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| Published in: | Japanese Journal of Applied Physics Vol. 51; no. 9; pp. 09LE07 - 09LE07-5 |
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| Main Authors: | , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
The Japan Society of Applied Physics
01-09-2012
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| Online Access: | Get full text |
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| Summary: | Scanning nonlinear dielectric microscopy is a powerful technique for measuring the domain structure of ferroelectrics. We observed congruent LiTaO 3 and found the marked enhancement of nonlinear dielectric "constants" when the applied tip--sample voltage exceeded a particular threshold value. This is due to domain nucleation activated by a huge electric field under the tip. Moreover, low frequencies (less than a few hundred Hz) did not enhance the nonlinearity. An effectively lower electric field caused by ion conduction in the sample under the tip is a possible reason for the frequency-dependent characteristics of the enhanced nonlinearity for the applied voltage. |
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| Bibliography: | A schematic of SNDM based on the contact-mode AFM. Examples of acquired images of CLT. The amplitude $V_{\text{p}}$s were (a) $V_{\text{p}} = 5$ V \text{pp and (b) $V_{\text{p}} = 15$ V \text{pp . In all images, the dark and bright contrasts represent the positive and negative signals, respectively. In the measurement of each $V_{\text{p}}$, the $1\omega_{\text{p}}$--$4\omega_{\text{p}}$ images were obtained by successively switching the order of demodulated signal, i.e., the images from $1\omega_{\text{p}}$ to $4\omega_{\text{p}}$ were taken in from the 1st to 4th quarters of a scanned area. Dependence of the signal of each harmonic on the amplitude $V_{\text{p}}$ and polarity of domain. (a) $1\omega_{\text{p}}$, (b) $2\omega_{\text{p}}$, (c) $3\omega_{\text{p}}$, (d) $4\omega_{\text{p}}$. Owing to noise of the system, (b) and (c) started from $V_{\text{p}} = 3$ V \text{pp and (d) started from $V_{\text{p}} = 5$ V \text{pp . Acquired $4\omega_{\text{p}}$ image at DC biases +5 and 0 V and constant amplitude $V_{\text{p}} = 10$ V \text{pp . Acquired $4\omega_{\text{p}}$ image at DC biases +5 and 0 V and constant amplitude $V_{\text{p}} = 10$ V \text{pp . Frequency characteristics of $1\omega_{\text{p}}$ signal in $+c$ domain. The frequency range is from 10 Hz to 23 kHz. This frequency range is within the bandwidth of the measurement system. Mechanism of compensation of the slowly changing electric field. |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.51.09LE07 |