Photoemission And Band-Calculation Studies Of The Charge-Density Wave In Cuv2s4

We have studied the electronic structure and its changes across the charge-density-wave (CDW) transition in spinel-type CUV2S4 by photoemission spectroscopy and first-principles band-structure calculations. The photoemission spectra show pseudogap-like behavior and the gap size is estimated to be similar to 90 meV. The large energy scale of the pseudogap compared to the transition temperature and its anomalous temperature dependence implies that the involved interaction is in the strong-coupling regime. The calculated electronic susceptibility chi (q) shows a small peak at q similar or equal to 11/40 [110], which is consistent with the observed wave vector q similar or equal to 1/4 [110] characterizing the CDW. This result suggests that Fermi surface nesting is at least partly responsible for the CDW formation.