Electron-loss spectroscopy has recently been used to investigate monocrystals of multilayered high-${\mathit{T}}_{\mathit{c}}$ superconductors, like ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{CaCu}}_2$${\mathrm{O}}_8$. The position of the plasmon peak has been measured as a function of the magnitude and orientation of the momentum transfer parallel to the ${\mathrm{CuO}}_2$ 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.

• Received 5 October 1992

DOI:https://doi.org/10.1103/PhysRevB.47.11611