Work

ARPES on Na0.6CoO2 : Fermi Surface and Unusual Band Dispersion

Year: 2004

Type: article

Abstract: The electronic structure of single crystals ${\mathrm{Na}}_{0.6}{\mathrm{CoO}}_{2}$, which are closely related to the superconducting ${\mathrm{Na}}_{0.3}{\mathrm{CoO}}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}y{\mathrm{H}}_{2}\mathrm{O}$ (${T}_{c}\ensuremath{\sim}5\text{ }\mathrm{K}$), is studied by angle-resolved photoelectron spectroscopy. While the measured Fermi surface (FS) is consistent with the large FS enclosing the $\ensuremath{\Gamma}$ point from the band theory, the predicted small FS pockets near the $K$ points are absent. In addition, the band dispersion is found to be highly renormalized, and anisotropic along the two principal axes ($\ensuremath{\Gamma}\mathrm{\text{\ensuremath{-}}}K$, $\ensuremath{\Gamma}\mathrm{\text{\ensuremath{-}}}M$). Our measurements also indicate that an extended flatband is formed slightly above ${E}_{F}$ along $\ensuremath{\Gamma}\mathrm{\text{\ensuremath{-}}}K$.

Source: Physical Review Letters

DOI: 10.1103/physrevlett.92.246403