Pseudogap and Superconductivity in Iron-Based Layered Superconductor studied by Fluctuation-Exchange Approximation

Abstract

We investigate interplay between magnetic fluctuations and superconductivity in the effective five-band Hubbard model for iron-oxypnictide superconductors on the basis of the fluctuation-exchange approximation. As for the normal-state properties, we find the pseudogap behavior in the NMR relaxation rate and the spectral weight in the electron-doped region, while we cannot find such behavior in the hole-doped region. The pseudogap behavior originates from the band structure effect, that is, existence of high density of states just below the Fermi level. Solving the superconducting Eliashberg equation, we find that the most probable candidate for the pairing symmetry is the sign-changed s-wave spin-singlet state. For small Hund's coupling J, the eigenvalue is not so sensitive to carrier doping, and seems to be irrelevant with antiferromagnetic (AF) spin fluctuation. We suggest that correlation between spin and spin-quadrupole is important as the pairing mechanism as well as the AF fluctuation.

5 pages, 8 figures

References in corpus (15)

• Superconductivity at 38 K in the iron arsenide (Ba1-xKx)Fe2As2
• Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems
• 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
• Observation of Fermi-surface-dependent nodeless superconducting gaps in Ba0.6K0.4Fe2As2
• Superconductivity up to 37 K in (A1-xSrx)Fe2As2 with A=K and Cs
• Is LaO${}_{1-x}$F${}_x$FeAs an electron-phonon superconductor ?
• Superconductivity at 25 K in hole doped $(L{a}_{1-x}S{r}_x)OFeAs$
• Evolution from Itinerant Antiferromagnet to Unconventional Superconductor with Fluorine Doping in La(O_{1-x}F_{x})FeAs Revealed by ^{75}As and ^{139}La Nuclear Magnetic Resonance
• ${}^{75}$As NMR studies of superconducting LaO${}_{0.9}$F${}_{0.1}$FeAs
• Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs
• Ab initio Derivation of Low-energy Model for Iron-Based Superconductors LaFeAsO and LaFePO
• Superconducting Gap and Pseudogap in Iron-Based Layered Superconductor La(O${}_{1-x}$F${}_x$)FeAs
• 59-Co and 75-As NMR Investigation of Electron-Doped High Tc Superconductor BaFe(1.8)Co(0.2)As(2) (Tc = 22K)
• On the Superconductivity of LaFe1-yCoyAsO1-xFx

Cited by in corpus (15)

• To What Extent Iron-Pnictide New Superconductors Have Been Clarified: A Progress Report
• Microwave Surface-Impedance Measurements of the Magnetic Penetration Depth in Single Crystal Ba1-xKxFe2As2 Superconductors: Evidence for a Disorder-Dependent Superfluid Density
• Momentum dependence and nodes of the superconducting gap in iron-pnictides
• Psuedo-isotropic upper critical field in cobalt-doped SrFe2As2 epitaxial films
• Strong-coupling Spin-singlet Superconductivity with Multiple Full Gaps in Hole-doped Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ Probed by Fe-NMR
• 75As NMR Study of Hole-Doped Superconductor Ba1-xKxFe2As2 (Tc = 38K)
• Antiferromagnetism of SrFe2As2 studied by Single-Crystal 75As-NMR
• Lower Critical Fields of Superconducting PrFeAsO${}_{1-y}$ Single Crystals
• Impurity-induced in-gap state and Tc in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors
• Theory of Raman response in a superconductor with extended s-wave symmetry: Application to Fe-pnictides
• Perturbation Theory of High-Tc Superconductivity in Iron Pnictides
• Systematic ^{75}As NMR study of the dependence of low-lying excitations on F doping in the iron oxypnictide LaFeAs(O_{1-x}F_{x})
• Penetration depth, lower critical fields, and quasiparticle conductivity in Fe-arsenide superconductors
• Normal State Spin Dynamics of Five-band Model for Iron-pnictides
• Unscreening Effect on Fe-Pnictide Superconductor