Electron-phonon interaction in the new superconductors La2−x(Ba,Sr)xCuO4

Abstract

A realistic tight-binding theory, based on the first-principles energy-band results of Mattheiss, is used to study the electron-phonon interaction in the new high-${\mathrm{T}}_{\mathrm{c}}$ superconductors ${\mathrm{La}}_{2\mathrm{-}\mathrm{x}}$(Ba,Sr${)}_{\mathrm{x}}$ ${\mathrm{CuO}}_4$. The calculated results include the phonon dispersion curves, phonon linewidths, the Eliashberg function ${\mathrm{\alpha }}^2$(ω)F(ω), and the interaction constant λ. A very strong couplin of specific O phonons to the conduction electrons is found (λ≥2), leading—because of the light oxygen mass—to ${\mathrm{T}}_{\mathrm{c}}$ values of ∼30-40 K.