ARPES study of CDW energy gap in 2H-TaS2

We have conducted temperature dependent Angle Resolved Photoemission Spectroscopy (ARPES) study of the electronic structure of 2H-TaS2, a canonical Charge Density Wave (CDW) system. We have mapped its entire Fermi surface, from which it is evident that CDW order in 2H-TaS2 is not due to Fermi surface nesting. Similar conclusion has been reached for 2H-NbSe2 in a number of recent studies. Our measurements have detected particle-hole asymmetric~CDW energy gap around the entire K-centric Fermi surface, however, no energy gap was detected around the Gamma-centric Fermi surface. Furthermore, our temperature-dependent measurement shows that the CDW energy gap persists even above the CDW transition temperature, which is similar to what has been observed in case of~2H-NbSe2.