Even Parity, Orbital Singlet, and Spin Triplet Pairing for SuperconductingLaFeAsO1−xFx

We examine the spin-triplet superconducting state of even parity mediated by ferromagnetic Hund’s coupling between electrons in two almost degenerate orbital bands. This state may be realized in the recently discovered ${\mathrm{LaFeAsO}}_{1-x}{\mathrm{F}}_x$. It is robust against orbital-independent disorder. The splitting of the orbital degeneracy suppresses superconductivity and leads to an anisotropic spectrum in the Bogoliubov quasiparticle. The former predicts a strong pressure dependence of $T_c$ and the latter predicts Fermi pockets, which may be tested in angle resolved photoemission spectra.