Recently, several measurements of the nuclear spin lattice relaxation rate T1−1 in the newly discovered superconducting Fe-pnictides have been reported. These measurements generally show no coherence peak below Tc and indicate a low temperature power law behavior, the characteristics commonly taken as evidence of unconventional superconductivity with lines of nodes crossing the Fermi surface. In this work we show that (i) the lack of a coherence peak is fully consistent with the previously proposed nodeless extended s±-wave symmetry of the order parameter (whether in the clean or dirty limit) and (ii) the low temperature power law behavior can be also explained in the framework of the same model, but requires going beyond the Born model.
@article{arxiv.0807.3729,
title = {NMR relaxation rate in superconducting pnictides: extended $s_{\pm}$ scenario},
author = {D. Parker and O. V. Dolgov and M. M. Korshunov and A. A. Golubov and I. I. Mazin},
journal= {arXiv preprint arXiv:0807.3729},
year = {2008}
}
Comments
5 pages, 4 figures (We have dropped the oversimplified Dynes' model for the unitary limit. Rather, we now treat the Born, unitary, and intermediate regimes on the same footing)