Theoretical Investigation of Superconductivity Properties of Sr1−xKxFe2As2: A Two-Band Green's Function Approach

The main objective of this research article is to investigate the superconductivity properties of Sr_{1 − x}K_xFe₂As₂ superconductor by employing a two-band Hamiltonian model and using Green's function (GF) formalism. Mathematical expressions are derived for key properties such as the superconducting (SC) order parameters, the SC transition temperature, the density of states (DOS), and condensation energy. Utilizing these expressions, Matplotlib in Python is employed to generate phase diagrams illustrating the SC order parameters versus temperature, the SC transition temperature versus SC coupling paramete, the DOS versus excitation energy, and the condensation energy versus the SC transition temperature, temperature, and inter-band pairing potential. These phase diagrams reveal key findings. First, both the SC order parameters and the condensation energy exhibit a decreasing trend as the temperature increases and vanish completely at the SC critical temperature. Second, the DOS initially increases with increasing excitation energy, until it reaches zero temperature SC order parameter (Δ(0)), which corresponds to the energy gap at zero temperature. Beyond this point, the DOS starts to decrease. Finally, the phase diagrams illustrate that the SC transition temperature increases as each intra-inter-band pairing potential increases.