Abstract
Polar materials display a series of interesting and widely exploited properties owing to the inherent coupling between their fixed electric dipole and any action that involves a change in their charge distribution. Among these properties are piezoelectricity, ferroelectricity, pyroelectricity, and the bulk photovoltaic effect. Here we report the observation of a related property in this series, where an external electric field applied parallel or anti-parallel to the polar axis of a crystal leads to an increase or decrease in its second-order nonlinear optical response, respectively. This property of electric-field-modulated second-harmonic generation (EFM-SHG) is observed here in nanowires of the polar crystal ZnO, and is exploited as an analytical tool to directly determine by optical means the absolute direction of their polarity, which in turn provides important information about their epitaxy and growth mechanism. EFM-SHG may be observed in any type of polar nanostructures and used to map the absolute polarity of materials at the nanoscale.
| Original language | English |
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| Article number | 3286 |
| Number of pages | 10 |
| Journal | Nature Communications |
| Volume | 12 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2 Jun 2021 |
Funding
The authors thank Dr. David Ehre and Prof. Igor Lubomirsky for helpful discussions. This research was supported by the European Research Council (ERC) Advanced Grants (No. 338849 and No. 669941), Israel Science Foundation (No. 2444/19) Helen and Martin Kimmel Centre for Nanoscale Science, Moskowitz Centre for Nano and Bio-Nano Imaging, the Crown Centre of Photonics and the Carolito Stiftung. E.J. holds the Drake Family Professorial Chair of Nanotechnology. D.O. is the incumbent of the Harry Weinrebe professorial chair of laser physics. R.B.Z. acknowledges funding from the Clore Foundation.