Density of state and effect of external magnetic field on co-existence state of SC and AFM in high- cuprates

A mean field Hamiltonian model is taken for our system to study density of states and the effect of external magnetic field on superconductivity (SC) and antiferromagnetism (AFM) at the co-existence stage in high- T c cuprates. The order parameters corresponding to SC and AFM long range orders are determined. The variation of dimensionless superconducting gap ( z ) and AFM gap ( h ̃ ) with temperature are investigated at different magnetic fields. The gap parameters are found to be strongly coupled to each other through their coupling constants. The interplay displays a BCS type of two gaps in the quasi-particle density of states which resemble the tunneling conductance of the STM experiment. The two gap edges in the density of states(DOS) appear at ± ( h ̃ 2 + z ) and ± ( h ̃ 2 − z ) . The effect of external magnetic field on DOS is also studied.