Using both two orbital and five orbital models, we investigate the quasiparticle interference (QPI) patterns in the superconducting (SC) state of iron-based superconductors. We compare the results for nonmagnetic and magnetic impurities in sign-changed $s$-wave $\text{cos}\left(k_x\right)\cdot \text{cos}\left(k_y\right)$ and sign-unchanged $\left|\text{cos}\left(k_x\right)\cdot \text{cos}\left(k_y\right)\right|$ SC states. While the patterns strongly depend on the chosen band structure details, the sensitivity of peaks around $\left(\pm \pi ,0\right)$ and $\left(0,\pm \pi \right)$ wave vectors on magnetic or nonmagnetic impurities, and on sign-changed or sign-unchanged SC orders is a common feature. Our results suggest that the QPI can provide evidence of the pairing symmetry in the SC states.

• Received 14 March 2009

DOI:https://doi.org/10.1103/PhysRevB.80.094528