Physical Review B 81,1 (2010)
We report the electronic structure of the iron-chalcogenide superconductor, Fe-1.04(Te0.66Se0.34), obtained with high-resolution angle-resolved photoemission spectroscopy and density-functional calculations. In photoemission measurements, various photon energies and polarizations are exploited to study the Fermi surface topology and symmetry properties of the bands. The measured band structure and their symmetry characters qualitatively agree with our density-functional theory calculations of Fe (Te0.66Se0.34), although the band structure is renormalized by about a factor of three. We find that the electronic structures of this iron chalcogenides and the iron pnictides have many aspects in common; however, significant differences exist near the Gamma point. For Fe1.04Te0.66Se0.34, there are clearly separated three bands with distinct even or odd symmetry that cross the Fermi energy (E-F) near the zone center, which contribute to three holelike Fermi surfaces. Especially, both experiments and calculations show a holelike elliptical Fermi surface at the zone center. Moreover, no sign of spin density wave was observed in the electronic structure and susceptibility measurements of this compound.
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