Charge-density wave gap and Ce 4f states in Ce Te2 observed by photoemission spectroscopy

The electronic structure of an f -electron charge-density-wave (CDW) system, Ce Te2, has been investigated using high-resolution angle-resolved photoemission spectroscopy (ARPES). Two gaps of ∼100 and ∼500 meV have been observed both along ΓX and ΓY, implying the 2×2 lattice deformation in the Te(1) sheets with the CDW gap of ≈100 meV. By employing the fine-structure (FS) resonance, the experimental Ce 4f ARPES spectra have been measured. The FS resonance ARPES shows a typical two-peak structure with the peaks at ∼-4 and ∼-1 eV, and the weight shift in the latter peak in contrast to the traditional giant resonance. The Ce 4f states have the negligibly small intensity near EF, reflecting the minor contribution from Ce 4f electrons to the metallic ground state of Ce Te2. This study reveals that the carriers near EF should have mainly the Te(1) 5p and Ce 5d character, but that only the Ce 5d bands cross EF.