On the isotope effect in some cuprate superconductors

The combined mechanism involving phonon and lochon (local charged boson) induced pairing of fermions developed earlier for cuprate superconductors is used to study the variation of the oxygen isotope effect (α-0) in these systems. The recently observed results for some cuprates are in agreement with the calculated trend in which (α0) tends to larger value when the critical temperature (Tc) is reduced by appropriate doping. These results support the combined phononic and electronic (lochonic) mechanism for cuprates with the latter dominating in the higher Tc regions. (author). 9 refs., 1 fig