Multiband magnetism and superconductivity in Fe-based compounds

Recent discovery of superconductivity in Fe-based layered compounds may have opened a new pathway to the room temperature superconductivity. A model Hamiltonian describing FeAs layers is introduced, highlighting the crucial role of puckering of As atoms in promoting d electron itinerancy and warding off large local-moment magnetism of Fe ions, the main enemy of superconductivity. Quantum many-particle effects in charge, spin and multiband channels are explored and a nesting-induced spin density-wave order is found in the parent compund. We argue that this largely itinerant antiferromagnetism and high T c itself are essentially tied to the multiband nature of the Fermi surface.