Extraction of a clean charge-density-wave gap for 2H-NaxTaS2NaxTaS2

We develop a novel decomposition method to extract a clean charge-density-wave (CDW) gap of sodium doped 2H-TaS2 from its partially suppressed photoemission spectra in the CDW state. We find that about 13 of the spectrum is fully gapped, while the other 23 is ungapped. Our results are in contrary to a recent theoretical proposal based on the band picture that divides the system into three decoupled sublattices, with two being distorted due to the CDW formation.