The study of spin-density-wave (SDW) and superconducting order parameter is a core topic for research on the FeAs-based high Tc superconductors. By using mathematical model Hamiltonian for the system and Green’s function formalism (creation and annihilation operators), we have obtained expressions for superconducting transition temperature (TC), spin density wave transition temperature (Tsdw), superconductivity order parameter (ΔSc), and spin density wave order parameter (Δsdw). By subjecting the experimental and theoretical values of the parameters in the obtained expressions, phase diagrams for superconducting transition temperature (TC) versus superconducting order parameter (ΔSc) and spin density wave transition temperature (Tsdw), versus spin density wave order parameter (Δsdw) have been plotted. Here we depicted that for the Ba1−xKxFe2As2system, the SDW and superconductivity can coexist in an extended range of compositions.

Keywords: Coexistence, order parameters, retarded Green function Pnictides Ba1−xKxFe2As2 , Superconductivity, Spin density wave (SDW)