Berlin 2015 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 11: Small Polarons in LiNbO3
DF 11.8: Vortrag
Mittwoch, 18. März 2015, 12:00–12:20, EB 133C
Temperature dependence of small polaron transport in Fe-doped lithium niobate — •Simon Messerschmidt, Felix Freytag, Holger Badorreck, and Mirco Imlau — Department of Physics, Barbarastraße 7, 49069 Osnabrück
Small bound NbNb4+, NbLi4+ electron and O− hole polarons are generated by single ns-laser pulses (2.5 eV) in Fe-doped lithiumniobate, LiNbO3 (source: Univ. Padova, Italy), thus, inducing a pronounced change of the macroscopic absorption αli. Inspection of the temporal decay αli(t) at photon energies characteristic for the specific polaron species allows to get insight to small polaron transport features and mutual recombination processes. Although, however, comprehensive studies on hopping processes at room and elevated temperature are available (270−400 K, Merschjann et al.. Phys. Rev. Lett. 96, 186404 (2006) and Refs. therein), studies of αli(t) at low temperatures are missing. The temperature range between 20−300 K particularly is of interest for transport studies as freezing of small polaron hopping accompanied by a predominance of tunneling is to be expected. We here present our systematic study in this temperature range by means of transient absorption spectroscopy and discuss our findings, i.e. pronounced changes in the recombination lifetime as well as of the shape of αli(t), using the Holstein model, Emin’s polaron theory and established recombination models in presence of Fe-doping (Herth et al., Phys. Rev. B 71, 125128 (2005)). Financial support by the DFG (IM37/5-2, INST 190/165-1 FUGG) is gratefully acknowledged.