SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 62: Ultrafast Dynamics of Light-Driven Systems
TT 62.7: Vortrag
Freitag, 31. März 2023, 11:15–11:30, HSZ 03
Driven lattice fluctuations in quantum paraelectric SrTiO3 — •Michael Fechner1, Michael Först1, Ankit Disa1, Michele Buzzi1, Alex von Hoegen1, Gal Orenstein2, Viktor Krapivin2, Quỳnh Le Nguyen2, Roman Mankowsky3, Mathias Sander3, Henrik Lemke3, Yunpei Deng3, Mariano Trigo2, and Andrea Cavalleri1 — 1Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany — 2Stanford Linear Accelerator Center, Menlo Park, United States of America — 3Paul Scherrer Institute, Villigen, Switzerland
Enhanced fluctuations are the precursors of quantum phase transition. In the case of ferro- and antiferrodistortive structural transitions, these fluctuations arise at specific points in reciprocal space. Here we use time-resolved x-ray diffuse scattering to show how a resonantly driven zone center optical phonon in cubic SrTiO3 selectively modulates lattice fluctuations at the Brillouin zone boundary. On short time scales, enhanced and oscillating lattice fluctuations are found at the R-point, which reduce to below the equilibrium value on the picosecond time scale. We attribute the fast dynamics to a finite-momentum fourth-order phonon-phonon interaction between the driven infrared-active Ti-O stretch mode and the antiferrodistortive zone-boundary soft mode. The long-term reduction indicates nonlinear coupling of the antiferrodistortive distortions to strain. We discuss the implications of these findings for the recently observed light-induced ferroelectric state of SrTiO3[1].
[1] T.F. Nova et al., Science 364, 1075 (2019)