Regensburg 2002 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 22: Postersitzung III: Syst. korr. Elektr.: Theorie II (1-15), Metall-Isol.- und Phasenüberg
änge (16-33), SL: Massivmat., Bandl., Pinning, Vortexdyn., Transport, Korngr. (34-43), Niedrigdim. Syst., Magnetotransport (44-63)

TT 22.49: Poster

Donnerstag, 14. März 2002, 14:00–17:30, A

Optical properties of quasi-one dimensional LaTiO3.4 — •C. A. Kuntscher1,2, D. van der Marel1, M. Dressel2, and F. Lichtenberg31Solid State Physics Laboratory, University of Groningen, The Netherlands — 21. Physikalisches Institut, Universität Stuttgart, Germany — 3Experimentalphysik VI, Universität Augsburg, Germany

Recently, the perovskite-related series SrNbO3.5−x (0≤x≤0.1) has attracted renewed attention, since one of its members, SrNbO3.4, turned out to have quite unusual low-energy electronic properties: It is a quasi-one dimensional (quasi-1D) metal which opens an extremely small energy gap at EF, as was shown by dc resistivity, optical spectroscopy, and ARPES [1]. The related compound LaTiO3.4 has a crystal structure very similar to that of quasi-1D SrNbO3.4, with the basic building blocks being slabs of corner-sharing TiO6 octahedra which extend parallel to the (a,b) plane. Within the slabs the octahedra are connected continuously via their apical oxygen atoms forming chains.

We have studied the polarization-dependent optical response of LaTiO3.4 as a function of temperature. For the polarization along the chains the optical conductivity σ1 contains characteristics also found for SrNbO3.4: a Drude contribution with superimposed vibrational fine structure and a strong mid-infrared band – characteristics which actually have been observed for many other quasi-1D metals. For the perpendicular polarization LaTiO3.4 shows an insulating behavior. We will present a comparison between the electronic properties of the two quasi-1D compounds LaTiO3.4 and SrNbO3.4.

[1] C. A. Kuntscher et al., cond-mat/0103485.

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