Spectral Consequences of Broken Phase Coherence in 1T- TaS_{2}

Abstract

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