Spin-triplet p-wave pairing in a three-orbital model for iron pnictide superconductors

We examine the possibility that the superconductivity in the newly discovered FeAs materials may be caused by the Coulomb interaction between d electrons of the iron atoms. We find that when the Hund's rule ferromagnetic interaction is strong enough, the leading pairing instability is in spin-triplet p-wave channel in the weak-coupling limit. The resulting superconducting gap has nodal points on the two-dimensional Fermi surfaces. The k dependent hybridization of several orbitals around a Fermi pocket is the key for the appearance of the spin-triplet p-wave pairing.