Quasi-one-dimensional plasmons in Cu-O chains - A possible reason for high-Tc superconductivity in YBa2Cu3O7

The plasmon mechanism of superconductivity is examined and shown to be particularly efficient in chain metals with a quasi-one-dimensional electron spectrum and anisotropic dispersion of plasma oscillations. In particular, the quasi-one-dimensional nature of the electron spectrum in linear Cu-O chains and the associated anisotropy of low-frequency plasmons may be responsible for the high-Tc superconductivity of compounds with the structure YBa2Cu3O7. These results are consistent with experimental observations of a reduction in Tc when oxygen content in the elementary cell is reduced to six atoms.