Dielectric response function in t- J- V model

Abstract

The dielectric response function ε{lunate} ( q, ω ) has been derived in the frame t - J - V model. In addition to the acoustic plasmon modes, a new collective charge excitation mode has been found. We have shown, that in layered cuprates the inverse dielectric function 1 / ε{lunate} ( q, ω ) may be negative in the area which partially overlaps the Fermi surface. Then, the interaction of quasiparticles via plasmon field causes the higher order harmonics in dx2 - y2-wave symmetry of the superconducting gap driven mainly by the superexchange interaction. © 2006 Elsevier B.V. All rights reserved.