SPECTRAL CONSEQUENCES OF BROKEN PHASE COHERENCE IN 1T-TAS2

Random defects destroy long-range phase coherence, and inhibit the met al-insulator transition in the charge density wave (CDW) system 1T-TaS 2. Photoelectron spectroscopy with high resolution reveals correspondi ng changes in the electronic structure. Core level spectra indicate a temperature-dependent limited growth of commensurate CDW domains. Scre ening by free carriers from the domain boundaries reduces the Coulomb repulsion in the Ta d band by similar to 1/3, compared to pure samples , yielding a finite spectral weight at the Fermi level.