0-$\pi$ phase shifts in Josephson junctions as a signature for the $s_{\pm }$-wave pairing state

Abstract

We investigate Josephson junctions with superconducting ferropnictides, both in the diffusive and ballistic limit. We focus on the proposed $s_{\pm }$-wave state, and find that the relative phase shift intrinsic to the $s_{\pm }$-wave state may provide 0-$\pi$ oscillations in the Josephson current. This feature can be used to discriminate this pairing state from the conventional s-wave symmetry. The 0-$\pi$ oscillations appear both as a function of the ratio of the interface resistances for each band and, more importantly, as a function of temperature, which greatly aids in their detection.

4 pages, 4 figures. Revised version with added results for ballistic limit. Accepted for publication in Phys. Rev. B - Rapid Communications