Impurity bound states and disorder-induced orbital and magnetic order in the s _± state of Fe-based superconductors

We study the presence of impurity bound states within a five-band Hubbard model relevant to iron-based superconductors. In agreement with earlier studies, we find that in the absence of Coulomb correlations there exists a range of repulsive impurity potentials where in-gap states are generated. In the presence of weak correlations, these states are generally pushed to the edges of the gap, whereas for larger correlations the on-site impurity potential induces a local magnetic region, which reintroduces the low-energy bound states into the gap.