Best wishes,
Arjan Berger

 

 

Advancements in laser technology have unlocked the potential to observe the real-time dynamics of nuclei on the femtosecond scale. Strontium titanate (SrTiO3) presents a unique case as a quantum paraelectric material, characterized by its near-ferroelectric transition at low temperatures, which is inhibited by quantum nuclear fluctuations. In this study, we simulate from first principles the time-resolved quantum nuclear dynamics of SrTiO3 under pulsed THz radiation targeting the mode responsible for ferroelectricity. Our novel first-principles approach based on the Time-Dependent Self-Consistent Harmonic Approximation (TD-SCHA)[1] not only accurately replicates the spectral features identified in time-resolved X-ray signals (like energy upconversion[2]) without any fitted parameter, but also reveals the complex energy redistribution processes among all modes following phonon-phonon scattering. We also show how it is possible to stabilize a dynamical ferroelectric phase[3,4] thanks to the transient strain induces by the nonlinear dynamics of nuclei.

 

[1] L Monacelli and F Mauri, Phys. Rev. B 103, 104305 (2021)

[2] M Kozina et al, Nat Phys, 15, 387 (2019)

[3] T F Nova et al, Science, 364, 1075 (2019)

[4] X Li et al, Science, 364, 1079 (2019)