Layer plasmons and high-Tcsuperconductivity

We study a layered electron-gas model for the high-$T_c$ copper oxides. The formation of plasmon bands by the interlayer Coulomb interaction is shown to lead to enhanced plasmon-induced electron pairing at the boundaries of the plasmon bands. We comment on the potential contribution of quasi-one-dimensional plasmons for the ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ compounds. The concept of coexistence of phonon and plasmon mechanisms is discussed.