The optical conductivity of single crystals of NaxCoO2 for x=0.57) is reported between 295 and 30 K. In the far infrared, an ‘‘anomalous Drude’’ analysis leads to a carrier effective mass of 561 electron masses. This high value is attributed to strong electron-phonon coupling, as suggested by the Fano distortion of a phonon at 570 cm-1. A peak at 8800 cm-1 scales with the charge transfer band of high-Tc cuprates by simply replacing the in-plane Cu-O bond length with that for Co-O.
OPTICAL CONDUCTIVITY OF SINGLE CRYSTALS OF Na(0.57)CoO(2) / Lupi, Stefano; Ortolani, Michele; Calvani, Paolo. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 69:(2004), pp. 1805061-1805064. [10.1103/PhysRevB.69.180506]