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Quasiparticle interference in iron-based superconductors

We systematically calculate quasiparticle interference (QPI) signatures for the whole phase diagram of iron-based superconductors. Impurities inherent in the sample together with ordered phases lead to distinct features in the QPI images that are believed to be measured in spectroscopic imaging-scanning tunneling microscopy (SI-STM). In the spin-density wave phase the rotational symmetry of the electronic structure is broken, signatures of which are also seen in the coexistence regime with both superconducting and magnetic order. In the superconducting regime we show how the different scattering behavior for magnetic and non-magnetic impurities allows to verify the $s^{+-}$ symmetry of the order parameter. The effect of possible gap minima or nodes is discussed.