Recent experiments have demonstrated that light can induce a transition from the quantum paraelectric to the ferroelectric phase of SrTiO3. Here, we investigate this terahertz field-induced ferroelectric phase transition by solving the time-dependent lattice Schr\"odinger equation based on first-principles calculations. We find that ferroelectricity originates from a light-induced mixing between ground and first excited lattice states in the quantum paraelectric phase. In agreement with the experimental findings, our study shows that the non-oscillatory second harmonic generation signal can be evidence of ferroelectricity in SrTiO3. We reveal the microscopic details of this exotic phase transition and highlight that this phenomenon is a unique behavior of the quantum paraelectric phase.
@article{arxiv.2106.03957,
title = {Simulating terahertz field-induced ferroelectricity in quantum paraelectric SrTiO$_3$},
author = {Dongbin Shin and Simone Latini and Christian Schafer and Shunsuke A. Sato and Edoardo Baldini and Umberto De Giovannini and Hannes Hubener and Angel Rubio},
journal= {arXiv preprint arXiv:2106.03957},
year = {2022}
}