Berlin 2015 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 4: Focused Session on Ferroic Domain Walls I (DF with MA)
DF 4.7: Vortrag
Montag, 16. März 2015, 17:40–18:00, EB 107
UV-induced AC transport along conductive domain walls in LiNbO3 single crystals — Mathias Schröder1, Xi Chen2, •Alexander Haußmann1, Andreas Thiessen1, Jan Poppe3, Dawn A. Bonnell2, and Lukas M. Eng1 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Str. 1, D-01069 Dresden, Germany — 2Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA — 3Physikalische Chemie, Technische Universität Dresden, Bergstrasse 66 b, D-01062 Dresden, Germany
The impedance properties of UV-illuminated (λ = 310 nm) conductive domain walls (CDWs) in 5% Mg-doped LiNbO3 single crystals (sc) are investigated both on the nm length scale using nanoimpedance microscopy (NIM), as well as macroscopically by comparing the transport properties of multi- and single domain samples. Similar to the DC transport, we find the CDWs to be highly conductive for AC currents as well, mostly pronounced for f < 200 Hz due to the strong influence of the bulk capacitance at higher frequencies. Moreover, simultaneously applying both an AC and DC voltage results in an increased real part of the AC CDW current. Equivalent circuits accurately describing both the domain and CDW contributions hence were developed; as a result we are able to analyze and quantify the complex dielectric conductive behavior of both bulk and CDWs in sc-LiNbO3 within the framework of the mixed conduction model: Hopping of excited charge carriers along the CDWs was identified as the dominant charge transport process.