Investigation of specific heat, density of states and superconducting gap parameters of mgb2 superconductor in two band models

The study focused on the theoretical investigation of superconducting gap parameters, density of states, electronic specific heat and condensation energy of two-band iron based superconductor MgB2. By developing a canonical two band BCS Hamiltonian containing a Fermi Surface of P(π)- and d(σ)-bands 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_p ), hole intra-band (Δ_d ), inter-band between the two bands (Δ_pd ) and superconducting transition temperature (T_C ). Furthermore, we obtained the density of states for each intra-band, N(ε), electronic specific heat (C_es)and condensation energy (E_c ) for MgB2. 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_p, Δ_d,Δ_pd versus temperature and superconducting transition temperature (T_C )versus the inter-band pairing potential (V_pd ) are plotted. We also plotted the density of states for the electron intra-band, N_p (ε)and hole intra-band, N_p (ε) versus excitation energy (ε) at T=0K, and the variation of density of states with temperature, electronic specific heat for the electron intra-band (C_p)and hole intra-band(C_p)versus temperature are plotted. 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.