Intense, few-cycle pulses in the terahertz frequency range have strong potential for schemes of control over vibrational modes in solid-state materials in the electronic ground-state. Here we report an experiment using single cycle terahertz pulses to directly excite lattice vibrations in the ferroelectric material Sn2P2S6 and ultrafast x-ray diffraction to quantify the resulting structural dynamics. A model of a damped harmonic oscillator driven by the transient electric field of the terahertz pulses describes well the movement of the Sn2+ ion along the ferroelectric soft mode. Finally, we describe an anharmonic extension of this model which predicts coherent switching of domains at peak THz-frequency fields of 790 kV/cm.
@article{arxiv.1602.05435,
title = {Ultrafast x-ray diffraction of a ferroelectric soft mode driven by broadband terahertz pulses},
author = {S. Grübel and J. A. Johnson and P. Beaud and C. Dornes and A. Ferrer and V. Haborets and L. Huber and T. Huber and A. Kohutych and T. Kubacka and M. Kubli and S. O. Mariager and J. Rittmann and J. I. Saari and Y. Vysochanskii and G. Ingold and S. L. Johnson},
journal= {arXiv preprint arXiv:1602.05435},
year = {2016}
}