An investigation on the role of some interactions in high tc superconductivity using extended t j model

Abstract

The present work describes an investigation on the role of some interactions in high- and#119879;and#119888; superconductivity using extended t- J model. The investigation is performed at a hole concentration and#9001;and#8462;and#9002;=0.25 which is appropriate for cuprates. The t- J model extended by nearest- neighbour (NN) Coulomb repulsion, density dependent correlated hopping interaction, electron pair hopping interaction between NN and next- nearest- neighbour (NNN) sites are studied. Both the ground state and the thermodynamic properties of the system are investigated. newlineIncluding the density dependent Coulomb repulsion interaction V (a t- J- V model), it is observed that d- wave pairing susceptibility (and#120594;and#119889;) decreases with Coulomb repulsion but increases with hole concentration. Hole- hole correlation decreases with distance of the sites but increases with hole concentration. A short range antiferromagnetic (AF) order present in the system is destroyed by inter- site Coulomb repulsion. The variation of pairing correlation lengths establishes that d- wave pairing mode is most suitable for high- and#119879;and#119888; superconductors. Effective exchange interaction (and#119869;and#119890;and#119891;and#119891;) decreases with Coulomb repulsion and hole concentration. newline