Effect of Pseudogap on the Interplay of Antiferromagnetism and d-Wave Superconductivity in High-T _c Cuprates

In the present report, we consider the model Hamiltonian consisting of antiferromagnetic and superconducting (SC) interactions for high-T _c cuprates in presence of band Jahn-Teller (JT) distortion as a pseudogap. The degeneracy of the cupper d-electrons is removed by the introduction of band Jahn-Teller distortion and hence the two non-degenerate bands acquire energy ε _k ±Ge with 'G' as the JT-coupling and 'e' as the lattice strain. The Hamiltonian is solved by using the Green's function technique of Zubarev. The gap equations for superconducting (SC), antiferromagnetic (AFM) and Jahn-Teller (JT) distortion energy are calculated and solved self-consistently for a set of coupling constants such that we obtain experimentally observed Neel temperature (T _N ), superconducting transition temperature T _c and lattice distortion temperature (T _s). It is observed that the AFM coupling appears as the SC coupling and enhances the SC transition temperature. The electronic density of states (DOS) explains the dip-hump structure observed in the tunneling conductance measurements and preserves its d-wave nature with node at the unbiased point. The DOS displays four distinct d-wave type gap structures and the gap edge energy values of these gaps help to calculate the individual order parameters and our calculations can interpret successfully the complex tunneling conductance spectra. The temperature dependent electronic specific heat shows three jumps corresponding to the transition temperatures of the antiferromagnetism, superconductivity and lattice distortion. The transition at T _c shows peak like jump exhibiting first order phase transition probably arising due to the pseudogap effect on superconducting gap.