We report an in-depth Angle Resolved Photoemission Spectroscopy (ARPES) study on 2H-TaS2, a canonical incommensurate Charge Density Wave (CDW) system. This study demonstrates that just as in related incommensurate CDW systems, 2H-TaSe2and 2H-NbSe2, the energy gap (Δcdw) of 2H-TaS2is localized along the K-centered Fermi surface barrels and is particle-hole asymmetric. The persistence of Δcdweven at temperatures higher than the CDW transition temperature Tcdwin 2H-TaS2, reflects the similar pseudogap (PG) behavior observed previously in 2H-TaSe2and 2HNbSe2. However, in sharp contrast to 2H-NbSe2, where Δcdwis non-zero only in the vicinity of a few "hot spots" on the inner K-centered Fermi surface barrels, Δcdwin 2H-TaS2is non-zero along the entirety of both K-centered Fermi surface barrels. Based on a tight-binding model, we attribute this dichotomy in the momentum dependence and the Fermi surface specificity of Δcdwbetween otherwise similar CDW compounds to the different orbital orientations of their electronic states that are involved in CDW pairing. Our results suggest that the orbital selectivity plays a critical role in the description of incommensurate CDW materials.
|Original language||English (US)|
|State||Published - May 7 2018|
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