The Signature of Weak Interband Coupling in Iron Pnictides: a Probe of the Superfluid Density

We study the temperature evolution behaviors of the superfluid density in the iron-based superconductors based on the two-orbital t − J1 − J2 model. It was revealed that the superfluid density exhibits the exotic positive curvature behavior when approaching Tc. The theoretical results are qualitatively consistent with the experimental observations. The positive curvature behavior of the superfluid density is attributed to the effects of the weak interband pairing coupling. Combining with the experimental observations, this indicates that the interband coupling strength is distinct between different iron-based compounds.