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Keywords:

  • High-temperature superconductivity;
  • Isotope effect;
  • Electron-phonon interaction

Abstract

The oxygen isotope effect in high-TC superconductors has been investigated on the basis of a two-band model where superconducting phase transition is induced by interband (mainly Coulombic) interaction. The isotope shift of TC appears due to the dependence of averaged interband electronphonon coupling constant on oxygen mass. This coupling has a repulsive nature and gives a relatively small contribution to the total interaction inducing superconductivity. The calculated isotope effect exponent depending on the carrier concentration has been compared with the experimental one as a function of x for La2-xSrxCuO4.