Jean-Marc Triscone awarded a honorary doctorate

by the Norwegian University of Science and Technology (NTNU)

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next Q-MAC meetings in 2018:

3rd Q-MAC symposium in Venice, May 22-25, 2018.

Next regular meeting in Paris, November 27-28, 2018.

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Publication Detail / Abstract

A. Subedi

Midinfrared-light-induced ferroelectricity in oxide paraelectrics via nonlinear phononics

published in Physical Review B on April 25, 2017
> Full text via publisher
I show that a nonequilibrium paraelectric to ferroelectric transition can be transiently induced using midinfrared pulses. This relies on a quartic l Qlz2Q hx2 coupling between the lowest (Qlz) and highest (Qhx) frequency infrared-active phonon modes of a paraelectric material. Density functional calculations show that the coupling constant l is negative, which causes a softening of the Qlz mode when the Qhx mode is externally pumped. A rectification along the Qlz coordinate that stabilizes the nonequilibrium ferroelectric state occurs only above a critical threshold for the electric field of the pump pulse, demonstrating that this is a nonperturbative phenomenon. A first-principles calculation of the coupling between light and the Qhx mode shows that ferroelectricity can be induced in the representative case of strained KTaO3 by a midinfrared pulse with a peak electric field of 17 MVcm−1 and duration of 2 ps. Furthermore, other odd-order nonlinear couplings make it possible to arbitrarily switch off the light-induced ferroelectric state, making this technique feasible for all-optic devices.
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