Odd-frequency pairing in the edge states of superconducting pnictides in the coexistence phase with antiferromagnetism

In some of the ferropnictide materials, spin-density wave order coexists with superconductivity over a range of doping and temperature. In this paper, we show that odd-frequency pairing emerges on the edges of pnictides in such a coexistence phase. In particular, the breaking of spin-rotation symmetry by spin-density wave and translation symmetry by the edge can lead to the development of odd-frequency spin-triplet Cooper pairing. In this case, the odd-frequency pairing has even-parity components, which are immune to disorder. Our results show that pnictides are a natural platform to realize odd-frequency superconductivity, which has been mainly searched for in heterostructures of magnetic and superconducting materials. The emergence of odd-frequency pairing on the edges and in the defects can be potentially detected in magnetic response measurements.