For a newly discovered iron-based high Tc superconductor LaFeAsO1-xFx, we have first constructed a minimal model, where all of the five Fe d bands turn out to be involved. We then investigate the origin of superconductivity with a five-band random-phase approximation by solving the Eliashberg equation. We conclude that the spin fluctuation modes arising from the nesting across the disconnected Fermi pockets realize an extended s-wave pairing, where, to be precise, the gap function is a 5 x 5 matrix.
ASJC Scopus subject areas
- Physics and Astronomy(all)