1210.7474 (Y. Wang et al.)

Using controlled disorder to distinguish $s_\pm$ and $s_{++}$ gap
structure in Fe-based superconductors    [PDF]

Y. Wang, A. Kreisel, P. J. Hirschfeld, V. Mishra

We reconsider the effect of disorder on the properties of a superconductor characterized by a sign-changing order parameter appropriate for Fe-based materials. Within a simple two band model, we calculate simultaneously $T_c$, the change in residual resistivity $\Delta \rho_0$, and the zero-energy density of states, and show how these results change for various types of gap structures and assumptions regarding the impurity scattering. The rate of $T_c$ suppression is shown to vary dramatically according to details of the impurity model considered. We search therefore for a practical, experimentally oriented signature of a gap of the $s_\pm$ type, and propose that observation of particular evolution of the penetration depth or NMR temperature dependence with disorder would suffice.

View original: http://arxiv.org/abs/1210.7474