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FM: Fachverband Funktionsmaterialien
FM 3: Focus Session: Novel mechanisms of ferroic switching (joint session MA/FM)
FM 3.4: Vortrag
Montag, 9. März 2026, 11:15–11:30, POT/0151
Coherent Control of Competing Structural Orders in SrTiO3 — •M. Fechner1, H. Wang2, M. Foerst1, G. Orenstein2, A. Disa3, M. Trigo2, and A. Cavalleri1 — 1Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany — 2Stanford Pulse Institute, SLAC National Accelerator Laboratory, Menlo Park, CA, USA — 3School of Applied & Engineering Physics, Cornell University, Ithaca, NY USA
The interplay between antiferrodistortive (AFD) rotation and polar instability prevents the formation of ferroelectric order in SrTiO3 yet keeps the paraelectric-to-ferroelectric transition on the verge of emerging. Light excitation has been shown to induce metastable ferroelectricity[1], but the response of the AFD order to such optical driving remains unclear. Here we use time-resolved X-ray scattering to track AFD-order dynamics, launched by mid-infrared excitation of the Ti-O stretching vibration, from 10 K to 135 K above the cubic transition. In the tetragonal phase below 110 K, the AFD order transiently increases before the AFD angle is reduced, whereas in the cubic phase rotational fluctuations initially grow before being strongly suppressed[2]. A unified lattice model, incorporating nonlinear coupling of the excited infrared phonon to the AFD mode and to strain, captures both regimes. With a single set of coupling parameters, we reproduce behaviors for both phases, indicating a common underlying mechanism that also constrains explanations for the light-induced ferroelectric state.
[1] T.F., et al. Nova Science 364, 1075 (2019), [2] M. Fechner, et al. NatMat, 23, 363 (2024)
Keywords: ferroic switching; nonlinear phononics; phonon excitation; THz dynamics; X-ray scattering