Pseudogapped Fermi surfaces of 1T-TaS2 and 1T-TaSe2:: A charge density wave effect -: art. no. 125117

We report room temperature angle-resolved photoemission experiments on 1T-TaS2 and 1T-TaSe2 complemented by density-functional theory calculations., Fermi-surface mapping experiments in the charge-density wave (CDW) phase are similar for the two compounds and do not show symmetries due to the CDW-induced new Brillouin zones. However, the band structure a few eV below the Fermi level (E-F) displays a clear modulation that we relate, in both cases, to the CDW. At E-F, the spectral weight distribution reflects the band structure of the normal state, but no clear quasiparticle crossing is located. Near the zone center (Γ) over bar, CDW-split quasilocalized Ta dz(2) subbands are observed in the vicinity of E-F. For 1T-TaS2 and 1T-TaSe2, they are thermally populated slightly above E-F and close to E-F, respectively. The observed behavior can be understood in terms of the CDW reconstructed, spectral function weighted band structure.