Theoretical study of the pairing mechanism in high tc cuprates and the role of pseudogap

Abstract

newline The discovery of the high-temperature superconductors is the epoch making event newlineof the present century in the field of condensed matter physics. Still then, it is newlinenot possible to discover the superconducting materials working at room temperature newlineand the mechanism of pairing in superconductivity is still not clear. A lot of both newlineexperimental and theoretical work has been going on. newlineWe have reviewed the discovery of the high-Tc superconductors, its structure and newlinethe interaction between the antiferromagnetism and superconductivity. Further, we newlinehave reviewed also the phase diagram under the different doping conditions. Then, we newlinepresent our theoretical models and the calculation of the different physical parameters newlineto desribe the cuprate superconducting systems. We consider the square lattice of the newlinecopper-oxide plane in tetragonal structure. When the copper-oxide planes are chained newlinein one direction, the copper-oxide planes become rectangular lattice with asymmetric newlinelattice parameters in the orthorhombic structure. Under these conditions we propose newlineour models to investigate the role of the antiferromagnetic orders in cuprate systems, newlineand try to understand specific heat at the low temperature anomaly in the system. newlineFinally, we propose a model Hamiltonian to study the interplay of the superconductivity newlineand antiferromagnetism in the orthrhombic lattice with an asymmetric parameter newlineor a structural distortion parameter in the electron hopping integrals. The physical newlineparameters are to be calculated by using Zubarev s Double time Green s functions newlinetechnique. The physical quantities thus calculated are then solved numerically by newlineself-consistent method. The results are presented in different chapters and finally the newlineviii