Antiferromagnetic and superconducting gaps of some superconductors

A theoretical model is presented to study the antiferromagnetic superconductors in which the effect of the impurity f-electrons and hybridization of the f-electrons with the conduction band are incorporated. The competition between magnetism and superconductivity is investigated in cuprate superconductors of the type R1−xMxCuO4 [R = La, Nd; M = Sr, Ba, Ce]. The antiferromagnetic long range ordering and the superconducting ordering are associated with the same conduction electrons and hence there is strong interplay between the two phenomena. Zubarev’s double time Green’s function technique and equations of motion method is used to evaluate the superconducting gap and antiferromagnetic staggered field. The interplay is studied by varying the coupling parameters, the position of the f-level and the hybridization. It is seen that the antiferromagnetic coupling enhances the superconducting order.