Band antiferromagnetism in a two-band model for iron pnictides

Abstract

In this work I investigate a two-band Hubbard model using the Gutzwiller wavefunction. The tight-binding part of the model was constructed to have a gapless spin-density wave state which leads to Dirac points in the bandstructure, a common feature of many iron-pnictide compounds. For quarter, half and three-quarter fillings I show that the Hund's rule coupling has a large impact on the metal-insulator transition in the paramagnetic phase. For the half-filled model in the antiferromagnetic phase, the magnetism evolves in a Stoner-like behavior and the size of the ordered moment is mainly determined by the Hubbard interaction. As the Hund's coupling plays a minor role in this state, the model does not describe a Hund's metal which is in contrast to more realistic models for iron-pnictide compounds.

6 pages, 6 figures

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