Berlin 2024 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 9: KFM Poster Session
KFM 9.38: Poster
Montag, 18. März 2024, 18:00–20:00, Poster E
Small polaron dynamics in lithium niobate tantalate in presence of optical damage — •Julian Koelmann1, Sören Domke1, Anton Pfannstiel1, Steffen Ganschow2, and Mirco Imlau1 — 1School of Mathematics/Informatics/Physics, Barbarastr. 7, Osnabrüuck University, Osnabrüuck, Germany — 2Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, Berlin, Germany
Optical damage is reported for the mixed crystal system LiNb1−xTax (0≤ x≤1) in accordance with the findings of its edge compositions lithium niobate (LN, x=0) and lithium tantalate (LT, x=1). Remarkably, the recording of e.g. holographic phase grating does not require doping with extrinsic deep centers such as FeLi3+/4+, that may be interpreted by a more pronounced landscape of intrinsic defects in LNT including the photo-excitation of small bound NbLi4+ and TaLi antisites. Simultaneously, the undisturbed optical characterisation of LNT, in particular the application of time-resolved fs-/ns-pump-probe spectroscopy to elucidate the dynamics of the electron-phonon interaction, is severely hampered. Here, we present our efforts to access small polaron dynamics despite the appearance of light-incuded, long-lived changes of the index of refraction and suppress its appearance by applying an appropriate pre-treatment protocol. As a result, the intensity dependence is accessed and a pronounced increase of the small polaron number density in comparison with LN and LT is clearly validated. Financial support by the DFG (project IM 37/12-1 of the research unit FOR 5044).
Keywords: Polarons; Lithium Niobate Tantalate; Optical Damage; Polar Oxides; Photorefractive Effects