THE DISPERSION-RELATIONS OF PLASMONS IN A SIMPLIFIED SYSTEM OF CUO2 LAYERS AND CU-O CHAINS

Abstract

A simplified model for YBa2Cu3O7 system composed of CuO2 layers and Cu-O chains has been calculated with the long range effect of the all-neighbors Coulombic e-e interactions taken into consideration. Dispersion relations have been worked out and discussed. The most striking consequence from the all-neighbors interaction is that the plasmons have, in the long wavelength limit, in addition to the usual vanishingly small two-dimensional acoustic plasmon energies which result from only nearest neighbor interactions, a non-zero omega(P)* consistent with the bulk plasma frequency of a three dimensional system. The data of an optical reflectance from an EELS experiment has been refitted based on calculated results for plasmon dispersion relations in the YBa2Cu3O7 system.