We report a comprehensive study of the tridimensional nature and orbital characters of the low-energy electronic structure in KCo2Se2, using polarization-and photon energy-dependent angle-resolved photoemission spectroscopy. We observed one electron-like Fermi surface (FS) at the Brillouin zone (BZ) center, four electron-like FSs centered at the BZ corner, and one hole-like FS at the BZ boundary. The FSs show weak dispersion along the k(z) direction, indicating the near-two-dimensional nature of FSs in KCo2Se2. In combination with the local-density approximation calculations, we determined the orbital characters of the lowenergy electronic bands, which are mainly derived from the Co 3d orbital, mixed with part of the Se 4p states. The d(x2-y2) orbital gives a significant contribution to the band crossing the Fermi level. A band renormalization of about 1.6 is needed to capture the essential dispersive features, which suggests that electronic correlations are much weaker than that in KyFe2-xSe2.
Chinese Academy of Sciences
; Ministry of Science and Technology of China
; National Science Foundation of China [11274381, 11004245]
; National Science Foundation [DMR-0537588]