Superconductivityand Magnetism In Lithium Iron Selenide Hydroxide (Li1-Xfex(Oh)Fe1-Yse) Superconductor In Two Band Model

Abstract

In this thesis, we describe the interplay between superconductivity and magnetism superconductor in Lithium Iron Selenide Hydroxide (Li1-xFex (OH) Fe1-ySe) was investigated theoretically. A two-band model Hamiltonian which represents the competing energies in the system was developed based on the electronic band structure of the system. The developed model Hamiltonian was solved employing the equation of motion approach of the retarded Green’s function. Using double time retarded Green`s function and the model Hamiltonian we obtained expression of superconducting transition temperature (Tc), superconducting order parameter ( ), magnetic transition temperature and magnetic order parameter ( ) mathematically. Numerically data were generated from these relations and plotted for discussion. Finally, we obtained the phase diagrams of superconducting transition temperature versus coupling constant, superconducting order parameter versus temperature, and superconducting transition temperature versus magnetic order parameter and magnetic transition temperature versus magnetic order parameter. Hence, the combined order parameter phase diagram is clearly shows the possible coexistence of superconductive and magnetism state in some range of parameter which is the brood agreement with experimental observation