Fermi surface of a quasi-one-dimensional oxide conductor

We report the first determination of the Fermi surface for a quasi-one-dimensional oxide conductor, ${\mathrm{Li}}_{0.9}$ ${\mathrm{Mo}}_6$ ${\mathrm{O}}_{17}$. The Fermi surface has been measured within the cleavage plane of the crystal using high-resolution angle-resolved photoemission spectroscopy. The Fermi surface consists of two parallel straight lines, separated by a nesting vector of approximately 0.7±0.05 A${\mathrm{̊}}^{\mathrm{-}1}$. A large density of states at ${\mathit{E}}_{\mathit{F}}$ is observed from the measured band dispersion, despite a low photoemission spectral intensity at ${\mathit{E}}_{\mathit{F}}$. The measured Fermi surface allows the prediction of the magnitude of the displacement vector associated with soft phonons and a postulated Peierls transition in ${\mathrm{Li}}_{0.9}$ ${\mathrm{Mo}}_6$ ${\mathrm{O}}_{17}$.