Spatial inhomogeneities in iron pnictide superconductors: The formation of charge stripes

The heterogeneous coexistence of antiferromagnetism [spin-density wave (SDW)] and superconductivity on a mesoscopic scale was observed in iron pnictides in many recent experiments. We suggest and discuss the scenario in which the heterogeneity is caused by formation of domain walls inherent to the SDW state of pnictides at a proper doping or under applied pressure. Superconductivity would emerge from the modulated SDW structure. The phenomenon is akin to the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) phase in superconductors.