Affiliation: | (1) Laboratorium für Festkörperphysik, ETH Zürich, 8093 Zürich, Switzerland;(2) Institut de physique de la matiére complexe (IPMC), EPF Lausanne, 1015 Lausanne, Switzerland;(3) Institute of Mineralogy and Geochemistry, University of Lausanne, 1015 Lausanne, Switzerland |
Abstract: | We present the optical properties of Na0.7CoO2 single crystals, measured over a broad spectral range as a function of temperature (T). The capability to cover the energy range from the far-infrared up to the ultraviolet allows us to perform reliable Kramers-Kronig transformation, in order to obtain the absorption spectrum (i.e., the complex optical conductivity). To the complex optical conductivity we apply the generalized Drude model, extracting the frequency dependence of the scattering rate () and effective mass (m *) of the itinerant charge carriers. We find that at low temperatures and for . This suggests that Na0.7CoO2 is at the verge of a spin-density-wave metallic phase.Received: 6 August 2004, Published online: 9 September 2004PACS: 78.20.-e Optical properties of bulk materials and thin films - 74.70.Dd Ternary, quaternary and multinary compounds (including Chevrel phases, borocarbides, etc.) - 75.30.Fv Spin-density waves |