VIOLATION OF ANDERSON’S THEOREM FOR SIGN-REVERSING S-WAVE STATE OF IRON-PNICTIDE SUPERCONDUCTORS

DOI: 10.1103/PhysRevLett.103.177001
Journal: Physical Review Letters
Year of Publication: 2009
Volume: 103
Issue: 17
Authors: Seiichiro OnariHiroshi Kontani

Abstruct

Based on the five-orbital model, we study the effect of local impurity in iron pnictides, and find that the interband impurity scattering is promoted by the d-orbital degree of freedom. This fact means that the fully-gapped sign-reversing s-wave state, which is predicted by spin fluctuation theories, is very fragile against impurities. In the BCS theory, only 1% impurities with intermediate strength induce huge pair-breaking, resulting in the large in-gap state and prominent reduction in Tc, contrary to the prediction based on simple orbital-less models. The present study provides a stringent constraint on the pairing symmetry and the electronic states in iron pnictides.

Keyword:
Superconductivity, Storongly correlated electron.