Impurity effect as a probe for order parameter symmetry in iron-based superconductors

The pointlike impurity scattering is studied for a superconductor with different pairing symmetries based on a minimal two band model proposed by S. Raghu et al. [Phys. Rev. B 77, R220503 (2008)], and the self-consistent Bogoliubov-de Gennes equations. Two intragap resonance peaks are found at or near the nonmagnetic impurity site for a typical sx2y2 symmetry and strong scattering potentials. Such intra-gap resonance peaks are absent for the sign unchanged s-wave and dx2−y2 -wave order parameter. Thus we propose that a nonmagnetic impurity with strong scattering potentials can be used to probe the pairing symmetry in iron-based superconductors. PACS numbers: 71.10.Fd, 74.20.-z Impurity effect as a probe for order parameter symmetry in iron-based superconductors 2