Summary: Ann. Phys. (Berlin) 523, No. 1 2, 8 50 (2011) / DOI 10.1002/andp.201000149
On the multi-orbital band structure and itinerant magnetism
of iron-based superconductors
Ole Krogh Andersen
and Lilia Boeri
Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
Received 7 November 2010, accepted 26 November 2010
Published online 4 January 2011
Key words Fe-based superconductors, electronic structure, tight-binding, downfolding, magnetism, inter-
This article is dedicated to Manuel Cardona.
This paper explains the multi-orbital band structures and itinerant magnetism of the iron-pnictide and
chalcogenide superconductors. We first describe the generic band structure of a single, isolated FeAs layer.
Use of its Abelian glide-mirror group allows us to reduce the primitive cell to one FeAs unit. For the lines and
points of high symmetry in the corresponding large, square Brillouin zone, we specify how the one-electron
Hamiltonian factorizes. From density-functional theory, and for the observed structure of LaOFeAs, we gen-
erate the set of eight Fe d and As p localized Wannier functions and their tight-binding (TB) Hamiltonian,
h(k). For comparison, we generate the set of five Fe d Wannier orbitals. The topology of the bands, i. e.
allowed and avoided crossings, specifically the origin of the d6
pseudogap, is discussed, and the role of the