Unusual spectral behavior of charge-density waves with imperfect nesting in a quasi-one-dimensional metal -: art. no. 066401

Low-temperature electronic properties of the charge-density-wave system NbSe3 are reported from angle-resolved photoemission at 15 K. The effect of two instabilities q(1) and q(2) on the k-resolved spectral function is observed for the first time. With a pseudogap background, the gap spectra exhibit maxima at Delta(1)(*)similar to110 meV and Delta(2)(*)similar to45 meV. Imperfectly nested sections of the Fermi surface lack a Fermi-Dirac edge, and show the signature of a dispersion that is modified by self-energy effects. The energy scale is of the order of the effective gap 2Delta(2)(*). The effect disappears above T-2, suggesting a correlation with the charge-density-wave state.