https://doi.org/10.1140/epjb/e2009-00148-9
Charge dynamics in quasi-one dimensional β-Sr1/6V2O5
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
Polarized infrared reflectivity was measured as a function of temperature on a quasi-one dimensional β-Sr0.17V2O5 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-Sr0.17V2O5 shows an insulator-like behaviour at all temperatures. The optical response is compared with the iso-electronic and iso-structural compound β-Na0.33V2O5. 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-Sr0.17V2O5. 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.
PACS: 78.20.-e – Optical properties of bulk materials and thin films / 71.38.-k – Polarons and electron-phonon interactions / 71.27.+a – Strongly correlated electron systems; heavy fermions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009