Fermi surface reconstruction in CeTe2induced by charge density waves investigated via angle resolved photoemission

Electronic structures of a charge-density wave (CDW) system CeTe${}_{2\ensuremath{-}x}$Sb${}_{x}$ ($x=0$, 0.05) have been investigated by employing angle-resolved photoemission spectroscopy (ARPES) and the first-principles electronic and phonon band-structure methods. The observed Fermi surface (FS) agrees very well with the calculated FS for the undistorted CeTe${}_{2}$ both in shapes and sizes. The metallic states crossing the Fermi level (${E}_{F}$) are observed in ARPES even in the CDW state. The carriers near ${E}_{F}$ have mainly the Te(1) $5p$ character, with a negligible contribution from Ce $4f$ states. The supercell (shadow) bands and the corresponding very weak FSs are found to arise from band folding due to the interaction of Te(1) layers with Ce-Te(2) layers. We found that the CDW modulation vector is along $\ensuremath{\Gamma}$-$X$ (${\mathbf{Q}}_{\text{CDW}}\ensuremath{\approx}X$), which is not coincident with the most prominent FS nesting vector.