Theoretical analyses of superconductivity in iron based superconductor Ba_1−xK_xFe₂As₂

This paper focuses on the theoretical analysis of superconductivity in iron based superconductor Ba 1−x K x Fe 2 As 2 . After reviewing the current findings on this system, we suggest that phononexciton combined mechanism gives a right order of  superconducting transition temperature (T C ) for Ba 1−x K x Fe 2 As 2 . By developing a model Hamiltonian for the system under consideration, using double time  temperature dependent Green’s function formalism and a suitable decoupling approximation technique, we have analyzed theoretically the superconductivity of iron-based superconductor Ba 1−x K x Fe 2 As 2 . Furthermore, by using the  experimental and plausible theoretical values of the parameters in the obtained expressions, phase diagrams of superconducting transition temperature (T C ) versus electron coupling constant (λe) and superconducting transition temperature (T C ) versus superconducting gap parameter (Δhave been plotted. Our findings demonstrate that, as the electron coupling constant (λe) increases the superconducting transition temperature (T C ) increases and vice versa and also as the temperature increases the superconducting order parameter decreases and vanishes at the transition temperature (T C ) for Ba 1−x K x Fe 2 As 2 . Our findings are in a broad agreement with the experimental observations. Keywords : Iron based Superconductors, Green’s Function formalism,   Superconducting order parameter, Ba 1−x K x Fe 2 As 2 .