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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Poster

KFM 14.21: Poster

Mittwoch, 19. März 2025, 17:00–18:30, P1

Long-lived, pulse-induced transient absorption in LiNb_1−xTa_xO₃ (0 ≤ x ≤ 1) solid solutions — •Julian Koelmann¹, Niklas Dömer¹, Mira Hesselink¹, Tobias Hehemann¹, Anton Pfannstiel¹, Felix Sauerwein^1,2, Laura Vittadello^1,2, 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 LiNb_1−xTa_xO₃ (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 Nb_Li⁵⁺, Ta_Li⁵⁺ antisites, and Ta_V⁵⁺ 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