Regensburg 2025 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 14: Poster
KFM 14.21: Poster
Wednesday, March 19, 2025, 17:00–18:30, P1
Long-lived, pulse-induced transient absorption in LiNb1−xTaxO3 (0 ≤ x ≤ 1) solid solutions — •Julian Koelmann1, Niklas Dömer1, Mira Hesselink1, Tobias Hehemann1, Anton Pfannstiel1, Felix Sauerwein1,2, Laura Vittadello1,2, Steffen Ganschow3, and Mirco Imlau1 — 1Institute of Physics, Barbarastr. 7, Osnabrück University, Osnabrück, Germany — 2Research Center for Cellular Nanoanalytics, Osnabrueck (CellNanOs), Osnabrueck University, Barbarastr. 11, Osnabrueck, 49076, Germany — 3Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, Berlin, Germany
Femto-/nanosecond pulse-induced, red and near-infrared absorption is studied in LiNb1−xTaxO3 (LNT) solid solutions with the aim of studying transient optical nonlinearities associated with optically generated small bound electron polarons. As a result, a long-lived transient absorption is uncovered for LNT which exceeds lifetimes and starting amplitudes of LiNbO3 (LN) and LiTaO3 (LT) by a significant factor. The transients provide strong evidence for an underlying hopping transport mechanism of small bound polarons. All findings are discussed in comparison to the model systems LN and LT within the framework of appropriate band models and optical generation of polarons via two-photon excitation. To explain the significant differences, the simultaneous presence of NbLi5+, TaLi5+ antisites, and TaV5+ interstitial defects is assumed for LNT. Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) * Project-ID 426703838 (IM 37/13-1, GA 2403/7-1 of the FOR 5044).
Keywords: Polarons; Lithium Niobate Tantalate; Polar Oxides; Transient Absorption Spectroscopy; Hopping Transport