THEORETICAL INVESTIGATION OF THE INTERACTION BETWEEN SUPERCONDUCTIVITY AND MAGNETISM IN SODIUM DOPED STRONTIUM IRON ARSENIDE (Sr1-xNaxFe2As2) SUPERCONDUCTOR IN TWO BAND MODEL.

ABSTRACT The study of the interplay between superconductivity and magnetism (AFM) has a special role in the ongoing investigation of how two electrons attracts each other and make pairs (mechanism) in unconventional superconductors. In the present work, the competition between superconductivity and magnetism (AFM) has been examined in sodium doped strontium iron arsenide (Sr1-xNaxFe2As2) superconductor by considering two band model Hamiltonian. Using retarded double time temperature dependent Green’s function formalism technique with the model Hamiltonian to obtain the mathematical expression for superconducting transition temperature (Tc), magnetic (AFM) transition temperature (Tm) and their corresponding order parameter have been obtained. With these expressions, the phase diagram of superconducting transition temperature as a function of magnetic order parameter and AFM transition temperature as a function of magnetic order parameter are plotted. The graph of superconducting transition temperature (Tc) as a function of magnetic order parameter ( ) shows that as magnetic order parameter increases the superconducting transition temperature decreases whereas the graph of magnetic transition temperature (Tm) as a function of magnetic order parameter reveals that the magnetic transition temperature increases with increases of magnetic order parameter. The merged phase diagram of superconducting transition temperature as a function of magnetic order parameter and magnetic transition temperature as a function of magnetic order parameter clearly shows that superconductivity and AFM are coexist in Sr1-xNaxFe2As2 superconductor in the region of magnetic order parameter between 3.6mev and 7.85mev which is well agree with the experimental results.