Possibility of Unconventional Pairing Due to Coulomb Interaction in Fe-Based Pnictide Superconductors: Perturbative Analysis of Multi-Band Hubbard Models

Abstract

Possibility of unconventional pairing due to Coulomb interaction in iron-pnictide superconductors is studied by applying a perturbative approach to realistic 2- and 5-band Hubbard models. The linearized Eliashberg equation is solved by expanding the effective pairing interaction perturbatively up to third order in the on-site Coulomb integrals. The numerical results for the 5-band model suggest that the eigenvalues of the Eliashberg equation are sufficiently large to explain the actual high Tc for realistic values of Coulomb interaction and the most probable pairing state is spin-singlet s-wave without any nodes just on the Fermi surfaces, although the superconducting order parameter changes its sign between the small Fermi pockets. On the other hand the 2-band model is quite insufficient to explain the actual high Tc.

2 pages, 3 figures. Proceedings of the Intl. Symposium on Fe-Oxypnictide Superconductors (Tokyo, 28-29th June 2008)

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Cited by in corpus (8)

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• Iron-Based Superconductors: current status of materials and pairing mechanism
• Impurity-induced in-gap state and Tc in sign-reversing s-wave superconductors: analysis of iron oxypnictide superconductors
• Surface density of states of s+-wave Cooper pairs in a two-band model
• Perturbation Theory of High-Tc Superconductivity in Iron Pnictides
• Surface Bound States in n-band Systems with Quasiclassical Approach
• Unscreening Effect on Fe-Pnictide Superconductor
• Impurity Scattering Rate and Coherence factor in Vortex Core of Sign-reversing s-wave Superconductors