A flat band at the chemical potential of a Fe1.03Te0.94S0.06 superconductor observed by angle-resolved photoemission spectroscopy

Abstract

The electronic structure of superconducting Fe1.03Te0.94S0.06 has been studied by angle resolved photoemission spectroscopy (ARPES). Experimental band topography is compared to the calculations using the methods of Korringa-Kohn-Rostoker (KKR) with coherent potential approximation (CPA) and linearized augmented plane wave with local orbitals (LAPW+LO). The region of the Gamma point exhibits two hole pockets and a quasiparticle peak close to the chemical potential with undetectable dispersion. This flat band with mainly dz2 orbital character is formed most likely by the top of the outer hole pocket or is an evidence of the third hole band. It may cover up to 3 % of the Brillouin zone volume and should give rise to a Van Hove singularity. Studies performed for various photon energies indicate that at least one of the hole pockets has a two-dimensional character. The apparently nondispersing peak at the chemical potential is clearly visible for 40 eV and higher photon energies, due to an effect of photoionisation cross section rather than band dimensionality. Orbital characters calculated by LAPW+LO for stoichiometric FeTe do not reveal the flat dz2 band but are in agreement with the experiment for the other dispersions around Gamma in Fe1.03Te0.94S0.06.

arXiv comment14 pages, 6 figures

References in corpus (32)

• High-temperature superconductivity in iron-based materials
• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• Superconductivity close to magnetic instability in Fe(Se1-xTex)0.82
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• Pressure evolution of low-temperature crystal structure and bonding of 37 K $T_c$ FeSe superconductor
• Probing the Low-Energy Electronic Structure of Complex Systems by ARPES
• Bulk Superconductivity at 14 K in Single Crystals of Fe1+yTexSe1-x
• Heavily electron-doped electronic structure and isotropic superconducting gap in AxFe2Se2 (A=K,Cs)
• Fe-based high temperature superconductivity with Tc=31K bordering an insulating antiferromagnet in (Tl,K)FexSe2 Crystals
• A review of Fe-chalcogenide superconductors: the simplest Fe-based superconductor
• Synthesis and crystal growth of Cs0.8(FeSe0.98)2: a new iron-based superconductor with Tc=27K
• Superconductivity without magnetism in LiFeAs
• Superconductivity in S-substituted FeTe
• Distinct Fermi Surface Topology and Nodeless Superconducting Gap in (Tl0.58Rb0.42)Fe1.72Se2 Superconductor
• Strong electron correlations in the normal state of FeSe0.42Te0.58
• Fermi surface topology and low-lying quasiparticle dynamics of parent Fe${}_{1+x}$Te/Se Superconductor by orbital-polarization resolved ARPES
• Fermi surface topology and low-lying quasiparticle structure of magnetically ordered Fe1+xTe
• Fe-based superconductors: an angle-resolved photoemission spectroscopy perspective
• Transport properties of the new Fe-based superconductor KxFe2Se2 (Tc = 33 K)
• Shallow pockets and very strong coupling superconductivity in FeSe_xTe_1-x
• Isotropic superconducting gaps with enhanced pairing on electron Fermi surfaces in FeTe0.55Se0.45
• Electronic Structure of Fe-Based Superconductors
• Electronic structure of Fe1.04(Te0.66Se0.34)
• Evidence for Three-Dimensionality in the Fermi Surface Topology of Layered Electron Doped Ba(Fe1-XCox)2As2 Iron Superconductors
• Common Fermi Surface Topology and Nodeless Superconducting Gap in K0.68Fe1.79Se2 and (Tl0.45K0.34)Fe1.84Se2 Superconductors Revealed from Angle-Resolved Photoemission Spectroscopy
• Orbital character variation of the Fermi surface and doping dependent changes of the dimensionality in BaFe2-xCoxAs2 from angle-resolved photoemission spectroscopy
• The scaling functions of the free energy density and its derivatives for the 3d O(4) model
• Evolution of superconductivity by oxygen annealing in FeTe0.8S0.2
• Interstitial Iron Controlled Superconductivity in Fe1+xTe0.7Se0.3
• Strong correlation and massive spectral-weight redistribution induced spin density wave in a-Fe1.06Te
• Measurement of Coherent Polarons in the Strongly Coupled Antiferromagnetically Ordered Iron-Chalcogenide Fe1.02Te using Angle-Resolved Photoemission Spectroscopy
• Superconductivity in oxygen-annealed FeTe1-xSx single crystal

Cited by in corpus (5)

• Non-Fermi-liquid scattering rates and anomalous band dispersion in ferropnictides
• Experimental evidence for the importance of Hund's exchange interaction for the incoherence of the charge carriers in iron-based superconductors
• Observation of an electron band above the Fermi level in FeTe${}_{0.55}$Se${}_{0.45}$ from \emph{in-situ} surface doping
• Electronic Structure of Fe${}_{1.08}$Te bulk crystals and epitaxial FeTe thin films on Bi${}_2$Te${}_3$
• Magnetism and Superconductivity of S-substituted FeTe