Impurity states in a family of antiferromagnetic iron arsenides

Abstract

In this paper, we explore theoretically the impurity states in antiferromagnetic spin-density wave states of iron arsenide. Two types of impurity models are employed: one has only intraband scattering, while the other has both intraband and interband scatterings with equal strength. Interestingly, the impurity bound state is revealed around the impurity site in the energy gap for both models. However, the impurity state is doubly degenerate with respect to spin for the first case, whereas the single-impurity state is observed in either the spin-up or spin-down channel for the second case. The impurity-induced variations of the local density of states are also examined. We propose scanning tunnelling microscopy (STM) measurements of the impurity state with the bound energy and spatial distribution of the wavefunction, which may shed light on the mechanism of the magnetically ordered phase. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.