Effect of external magnetic field on superconducting and spin density wave gaps of high- Tc superconductors

Abstract

A theoretical model is addressed here to study the interplay of the superconductivity (SC) and the spin density wave (SDW) long range orders in underdoped region in the vicinity of on-set of superconductivity in presence of an external magnetic field. The order parameters are calculated by using Zubarev’s technique of Green’s functions and determined numerically self-consistently. The gap parameters are found to be strongly coupled to each other through their coupling constants. The interplay displays BCS type two gaps in the quasi-particle density of states (DOS) which resemble the tunneling conductance of STM experiments. The gap edges in the DOS appear at ± ( z + z 1 ) and ± ( z - z 1 ) . The applied magnetic field further induces Zeeman splitting which is explained on the basis of spin-filter effect of tunneling experiment.