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TT: Tiefe Temperaturen
TT 7: Niedrigdimensionale Systeme
TT 7.4: Vortrag
Dienstag, 25. März 2003, 10:30–10:45, HSZ03
Signatures of polaronic excitations in quasi-1D LaTiO3.41 — •C. A. Kuntscher1,2, D. van der Marel1, M. Dressel2, and F. Lichtenberg3 — 1Material Science Center, University of Groningen, The Netherlands — 21. Physikalisches Institut, Universität Stuttgart, Germany — 3Institut für Physik, EKM, Universität Augsburg, Germany
Polaronic quasiparticles have been proposed to play an important role in exciting phenomena of the solid state, like high-Tc superconductivity and colossal magnetoresistance. Recent ARPES measurements [1] suggest that polarons also exist in quasi-1D metals and may explain the peculiar properties of these systems. For the verification of the polaronic picture we studied the optical response of the quasi-1D conductor LaTiO3.41 to search for polaronic signatures and test their compatibility with the existing models [2]. For the polarization along the conducting axis the optical conductivity contains a pronounced mid-infrared (MIR) band whose temperature dependence is similar to that of the MIR absorption in the cuprate superconductors and consistent with (interacting) polaron models. The polaron formation in LaTiO3.41 is corroborated by the presence of strong electron-phonon coupling and the temperature dependence of the dc conductivity. The fact that a band in the MIR frequency range is a characteristic feature in the optical spectrum of quasi-1D conductors suggests the general importance of polarons for the transport mechanism in these systems.
[1] L. Perfetti et al., Phys. Rev. Lett. 87, 216404 (2001).
[2] C. A. Kuntscher et al., cond-mat/0205049.