paper

Resonant impurity scattering in the s-gap state of the Fe-based superconductors

arXiv:0808.0302 · doi:10.1103/PhysRevB.79.054529

Abstract

We study the impurity scattering on the s-wave superconductor, with realistic parameters for the Fe-pnictide superconductors. Using -matrix method, generalized for the two bands, we found that impurity scattering of the unitary limit forms off-centered bound states inside of the superconducting gap, which modifies, surprisingly, the density of states (DOS) of a fully opened gap to a V-shaped one as in the case of a d-wave superconductor. This behavior provides coherent explanations to the several conflicting experimental issues of the Fe-pnictide superconductors: the V-shaped DOS but with an isotropic gap observed in the photoemission and tunneling experiments; the power law behavior of the nuclear spin-lattice relaxation rate ( ; ), down to very low temperatures.

5 pages, 3 figures, Revisions of Figures and their captions; references updated

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