Coexistence of Superconductivity and Antiferromagnetism in High-TC Gd1+xBa2−xCu3O7−δ Superconductor

Following the experimental discovery of the coexistence of superconductivity and antiferromagnetism in high- TC superconductor of fully oxygenated superconducting Gd1.2Ba1.8Cu3O7.03 by Rogacki, a theoretical study has been made by considering a model Hamiltonian consisting of pairing interaction, intra- and inter-atomic Coulomb interactions, exchange interaction, and a new interaction involving scattering of Cooper pairs by the magnetic moments/spins of Gd ions. Employing Green’s function formalism and a suitable decoupling approximation technique, the coexistence of superconductivity and antiferromagnetism has been shown to be a very distinct possibility. The phase diagrams of superconducting gap parameter (Δ) versus temperature (T) for various values of magnetic order parameter (η), the superconducting transition temperature (TC) and antiferromagnetism order temperature (TN) versus magnetic order parameter (η) have been plotted. Finally, by combining the two phase diagrams, the coexistence of superconductivity and antiferromagnetism has been demonstrated. The obtained result is in broad agreement with the experimental observations.