Evidence for a cos(4φ) Modulation of the Superconducting Energy Gap of Optimally Doped FeTe_{0.6}Se_{0.4} Single Crystals Using Laser Angle-Resolved Photoemission Spectroscopy

Abstract

We study the superconducting(SC)-gap anisotropy of the Γ-centered hole Fermi surface in optimally doped FeTe_{0.6}Se_{0.4} (T_c = 14.5 K), using laser-excited angle-resolved photoemission spectroscopy (ARPES). We observe sharp superconducting coherence peaks at T = 2.5 K. In contrast to earlier ARPES studies but consistent with thermodynamic results, the momentum dependence shows a \cos(4φ) modulation of the SC-gap anisotropy. The observed SC-gap anisotropy strongly indicates that the pairing interaction is not a conventional phonon-mediated isotropic one. Instead, the results suggest the importance of second-nearest-neighbor electronic interactions between the iron sites in the framework of s_\pm-wave superconductivity.

5 pages, 3 figures, published in Physical Review Letters

References in corpus (7)

• Unconventional pairing originating from disconnected Fermi surfaces in superconducting LaFeAsO${}_{1-x}$F${}_x$}
• LaFeAsO${}_{1-x}$F${}_x$: A low carrier density superconductor near itinerant magnetism
• Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity
• First-order magnetic and structural phase transitions in Fe${}_{1+y}$Se${}_x$Te${}_{1-x}$
• Electronic Structure and Doping in BaFe${}_2$As${}_2$ and LiFeAs: Density Functional Calculations
• Momentum dependence and nodes of the superconducting gap in iron-pnictides
• Anisotropic fluctuations and quasiparticle excitations in FeSe_0.5Te_0.5

Cited by in corpus (12)

• Electronic Structure and Superconductivity of FeSe-Related Superconductors
• Evidence for Helical Hinge Zero Modes in an Fe-Based Superconductor
• Correlation-Driven Electronic Reconstruction in FeTe${}_{1-x}$Se${}_x$
• On the origin of critical temperature enhancement in atomically-thin superconductors
• Anisotropic but nodeless superconducting gap in the presence of spin density wave in iron-pnictide superconductor NaFe1-xCoxAs
• Evolution from incoherent to coherent electronic states and its implications to superconductivity in FeTe1-xSex
• FeTe${}_{0.55}$Se${}_{0.45}$: a multiband superconductor in the clean and dirty limit
• Exceptional Suppression of Flux-Flow Resistivity in FeSe${}_{0.4}$Te${}_{0.6}$ by Back-Flow from Excess Fe Atoms and Se/Te Substitutions
• Orbital superconductivity, defects and pinned nematic fluctuations in the doped iron chalcogenide FeSe${}_{0.45}$Te${}_{0.55}$
• Structure of the pairing gap from orbital nematic fluctuations
• Two-band conductivity of a FeSe${}_{0.5}$Te${}_{0.5}$ film by reflectance measurements in the terahertz and infrared range
• Q Dependence of Magnetic Resonance Mode on FeTe${}_{0.5}$Se${}_{0.5}$ Studied by Inelastic Neutron Scattering