Single Impurity Effects in Multiband Superconductors with Different Sign Order Parameters
Abstract
A single impurity problem is investigated for multiband s-wave superconductors with different sign order parameters (+-s-wave superconductors) suggested in Fe-pnictide superconductors. Not only intraband but also interband scattering is considered at the impurity. The latter gives rise to impurity-induced local boundstates close to the impurity. We present an exact form of the energy of the local boundstates as a function of strength of the two types of impurity scattering. The essential role of the impurity is unchanged in finite number of impurities. The main conclusions for a single impurity problem help us understand effects of dense impurities in the +-s-wave superconductors. Local density of states around the single impurity is also investigated. We suggest impurity site nuclear magnetic resonance as a suitable experiment to probe the local boundstates that is peculiar to the +-s-wave state. We find that the +-s-wave model is mapped to a chiral dx2-y2+-idxy-wave, reflecting the unconventional nature of the sign reversing order parameter. For a quantum magnetic impurity, interband scattering destabilizes the Kondo singlet.
Keywords
Cite
@article{arxiv.0906.2639,
title = {Single Impurity Effects in Multiband Superconductors with Different Sign Order Parameters},
author = {Masashige Matsumoto and Mikito Koga and Hiroaki Kusunose},
journal= {arXiv preprint arXiv:0906.2639},
year = {2009}
}
Comments
23 pages, 7 figures, to be published in J. Phys. Soc. Jpn. (2009) No. 8