Electronic structure and anomalous photoemission line-shape of quasi-2D oxide η-Mo4O11

The η-Mo4O11 compound is a layered two-dimensional (2D) metallic system whose reduced dimensionality originates non-linear properties as charge density wave (CDW) instabilities. We report on synchrotron radiation angle resolved photoemission spectroscopy (ARPES) measurements in order to obtain a detailed picture of the electronic structure of this material. The symmetry of the states near the Fermi level (EF) has been discussed in relation to the photoemission symmetry selections rules. Our results are in excellent agreement with previous tight-binding calculations and support the hidden nesting concept proposed to explain the CDW instabilities exhibited by this family of compounds. In addition, a very peculiar photoemission line-shape has been found with the presence of localized non-dispersive states. Some possible explanations are discussed.