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

被引：116

作者：

Ikeda, Hiroaki ^{[1
]}

机构：

[1] Kyoto Univ, Dept Phys, Kyoto 6068502, Japan

来源：

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN | 2008年 / 77卷 / 12期

关键词：

iron-oxypnictide; superconductivity; FLEX; multiband Hubbard model; pseudogap;

D O I：

10.1143/JPSJ.77.123707

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

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. ne 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.

引用

页数：4

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