INTERPRETATION OF THE PLASMON DISPERSION IN THE ELECTRON-ENERGY-LOSS SPECTRA OF HIGH-TC SUPERCONDUCTORS

Electron-loss spectroscopy has recently been used to investigate monocrystals of multilayered high-T(c) superconductors, like Bi2Sr2CaCu2O8. The position of the plasmon peak has been measured as a function of the magnitude and orientation of the momentum transfer parallel to the CuO2 layer planes. In this paper it is shown that these spectra can be consistently interpreted if one uses a model taking into account the multilayered structure of the crystal as well as the square shape of the Fermi curve (for half-filled Brillouin zone). Moreover direct information can be obtained regarding the background dielectric constant, the effective mass of the charge carriers, and the Fermi energy.