No abstract

The correlated 3d sulphide BaVS 3 exhibits an interesting coexistence of one-dimensional and threedimensional properties. Our experiments determine the electronic band structure and shed light on this puzzle. High-resolution angle-resolved photoemission measurements in a 4-eV-wide range below the Fermi energy level uncover and investigate the coexistence of a 1g wide-band and e g narrow-band d electrons, which lead to the complicated electronic properties of this material. We explore the effects of strong correlations and the Fermi surface instability associated with the metal-insulator transition.

We have determined the electronic structure of ␣-Ga using angle-resolved photoemission from the ␣-Ga͑010͒ surface. Data were collected both at 78 K and at 273 K, i.e., below and above the temperature of the surface phase transition. We observe a number of relatively flat bands reflecting the partly covalent character of ␣-Ga. Our results agree fairly well with recent band-structure calculations.

No abstract

High-resolution angle-resolved photoemission ͑ARPES͒ displays quasi-one dimensional ͑1D͒ electronic states in the insulating molybdenum red bronze K 0.33 MoO 3 , in good qualitative agreement with band structure calculations. Combined ARPES, optical conductivity, and electrical resistivity data underline the importance of defects which pin the Fermi level within the gap. The ARPES line shape exhibits the same strong-coupling features observed in the blue bronze K 0.3 MoO 3 , a related 1D Peierls conductor. We speculate that a similar mechanism could be at the origin of the gaps in both materials.