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FM: Fachverband Funktionsmaterialien

FM 11: Poster Session Functional Materials

FM 11.31: Poster

Dienstag, 10. März 2026, 18:00–20:30, P4

Analysing the laser-driven tetragonal-to-cubic phase-transition in ferroelectric BaTiO₃ using EXAFS spectroscopy as a local probe — •Janosch Tasto¹, Rajdwip Bhar¹, Simon Rauls¹, Marco Reinhard², Dimosthenis Sokaras², Uwe Bovensiepen¹, and Heiko Wende¹ — ¹Faculty of Physics and CENIDE, University of Duisburg-Essen — ²SLAC National Accelerator Laboratory, Stanford University

This work aims to establish time-resolved Extended X-ray Absorption Fine Structure (tr-EXAFS) spectroscopy as a methodology for solids where the structural information of the EXAFS is combined with a pump-probe setup to study local dynamic lattice processes in the time domain.
As a proof of concept, we analyze the structural cubic-to-tetragonal phase-transition in the ferroelectric perovskite BaTiO₃. The coexistence of displacive and order-disorder phenomena accompanying this transition is a topic of debate in the literature on this extensively studied material.Difference-EXAFS scans at the Ti K-edge and the Ba L₃-edge between the pumped and unpumped state provide a direct way to investigate changes in lattice-structure and thermal-induced disorder in the vicinity of the absorbing atom. We correlate our spectroscopic findings with ab initio multiple-scattering calculations using the FEFF10 code to quantify structural dynamics.
We thank the Deutsche Forschungsgemeinschaft (in the framework of the Collaborative Research Center 1242) for financial support.

Keywords: XAS; EXAFS; barium titanate; ferroelectric; structural phase-transition