Doping dependent tunneling conductance in SDW ordered copper oxide superconductors

It is observed that doping suppresses the long range anti-ferromagnetic order and induces superconducting phase for a suitable doping. In order to study this effect, we present a model study of the doping dependence of the tunneling conductance in high-Tc systems. The system is described by the Hamiltonian consisting of spin density wave (SDW) and s-wave type superconducting interaction in presence of varying impurity concentrations. The gap equations are calculated by using Green’s functions technique of Zubarev. The gap equations and the chemical potential are solved self-consistently. The imaginary part of the electron Green’s functions shows the quasi-particle density of states which represent the tunneling conductance observed by the scanning tunneling microscopy (STM). We investigate the effect of impurity on the gap equations as well as on the tunneling conductance. The results will be discussed based on the experimental observations.

Research highlights
► The model calculation reports the co-existences of s-wave superconductivity and spin density wave (SDW) in high-Tc cuprates.
► The doping dependence of the phase diagram explains the experimental observations qualitatively.
► The calculated tunneling spectra explains the observed multiple peak structures.
► This calculation provides an alternative to BCS formalism to calculate order parameters from the spectra.