Eur. Phys. J. B 69, 181-186 (2009)
https://doi.org/10.1140/epjb/e2009-00148-9

Charge dynamics in quasi-one dimensional β-Sr_1/6V₂O₅

¹ Laboratoire d'électrodynamique des matériaux avancés, CNRS UMR 6157 – CEA, Université F. Rabelais, UFR Sciences – Parc de Grandmont, 37200 Tours, France
² Institut des Matériaux Jean Rouxel, UMR 6502 CNRS, Université de Nantes, BP 32229, 2, rue de la Houssinière, 44322 Nantes, France
³ DRFMC/SPSMS/IMAPEC – CEA Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex, France

Corresponding author: ^a taphuoc@univ-tours.fr

Received: 11 September 2008
Revised: 16 February 2009
Published online: 5 May 2009

Abstract

Polarized infrared reflectivity was measured as a function of temperature on a quasi-one dimensional β-Sr_0.17V₂O₅ single crystal. Along the conduction direction, the optical conductivity exhibits a weak electronic background in the far infrared and a large mid infrared band. Sum rule analysis shows that both far infrared and midinfrared bands arise from 3d vanadium electrons. As temperature is decreased, the mid infrared band slightly narrows and redshifts, but does not exhibit drastic change. In contrast, the spectral weight grows at low frequencies and peaks appear in the phonon energy range. In the transverse direction, β-Sr_0.17V₂O₅ shows an insulator-like behaviour at all temperatures. The optical response is compared with the iso-electronic and iso-structural compound β-Na_0.33V₂O₅. Although spectra are very similar in both compounds at room temperature, their temperature dependence differs. However, some general trends indicate that charge carriers are of the same nature in both compounds. The results suggest that electron- phonon coupling is relevant to explain the optical properties of β-Sr_0.17V₂O₅. The optical response along the conducting direction is assigned to an adiabatic small polaron absorption, in intermediate or strong electron-phonon coupling regime. In this framework, the optical conductivity is in qualitative agreement with recent Dynamical Mean Field Theory results over a wide temperature range.