Theoretical Study of Superconducting Gap Parameters, Density of States, and Condensation Energy of Two-Band Iron-Based Superconductor BaFe₂(As_1−xP_x)₂

This research work focuses on the theoretical study of superconducting gap parameters, density of states, and condensation energy of two-band iron-based superconductor BaFe₂(As_1−xP_x)₂. By developing a model Hamiltonian for the given system and by using the double time temperature-dependent Green's function formalism, we obtained mathematical expressions for superconducting order parameters for the electron intra-band (Δ_e), hole intra-band (Δ_h), inter-band between the two bands (Δ_eh) and superconducting transition temperature (T_C). Furthermore, we obtained the density of states for each intra-band, N(ε) and condensation energy (E_c) for BaFe₂(As_1−xP_x)₂. By using the experimental values and by considering some plausible approximations of the parameters in the obtained expressions, phase diagrams of superconducting order parameters for Δ_e, Δ_h, and Δ_eh versus temperature and superconducting transition temperature (T_C) versus the inter-band pairing potential (V_eh) are plotted. We also plotted the density of states for the electron intra-band, N_e(ε) and hole intra-band, N_h(ε) versus excitation energy (ε) at T = 0K, and the variation of density of states with temperature. Similarly, phase diagrams of condensation energy (E_c) versus temperature, inter-band pairing potential, and superconducting transition temperature are plotted for the material. Our results are in agreement with previous findings.