Effect of external magnetic field on the co-existence of superconductivity and antiferromagnetism in rare earth nickel borocarbides (RNi2B2C)

In this paper, we have studied the effect of external magnetic field in the co-existing phase of superconducting and antiferromagnetism (AFM) of rare earth nickel borocarbides. The AFM in these systems might have originated due to both localized "f" electrons as well as itinerant electrons which are responsible for conduction. On the other hand, superconductivity (SC) is due to spin density wave, arising out of Fermi surface instability. The AFM order is mostly influenced by hybridization of the "f" electron with the conduction electron. Here, we have obtained the dependence of superconducting energy gap as well as staggered magnetic field on temperature T and energy epsilon(k) in a framework based on mean field Hamiltonian using double time electron Green's function. We have shown in our calculation the effect of external magnetic field on superconducting and antiferromagnetic order parameters for YNi2B2C in the presence of hybridization. The ratio of the calculated effective gap and T-C is close to BCS value which agrees quite well with experimental results.