Hole superconductivity in arsenic–iron compounds

Superconductivity above 25 K, and possibly above 40 K, has recently been discovered in LaO1−xFxFeAs and related compounds. We propose that this is another example of the mechanism of hole superconductivity at play. This requires the existence of hole carriers at the Fermi energy, which appears to contradict current observations. We propose that two-band conduction is taking place in these materials, that the negative ion As−3 plays a key role, and that superconductivity is non-phononic and driven by pairing and undressing of heavily dressed hole carriers to lower their kinetic energy. We make several predictions of future observations based on our theory.