Superconductivity mediated by the antiferromagnetic spin wave in chalcogenide iron-based superconductors

The ground state of K0.8+xFe1.6+ySe₂ and other iron-based selenide superconductors are doped antiferromagnetic semiconductors. We propose that the low energy physics of this system is governed by a model Hamiltonian of interacting electrons with onsite ferromagnetic exchange interactions and intersite superexchange interactions. We have derived the effective pairing potential of electrons under the linear spin-wave approximation and shown that the superconductivity can be driven by mediating coherent spin-wave excitations in these materials. Our work provides a natural account for the coexistence of superconducting and antiferromagnetic long range orders observed by neutron scattering and other experiments.