Isotope effect in high-Tc materials:: role of non-adiabaticity and magnetic impurities

Based on previous calculations of the isotope effect (IE) in superconductors, we present a detailed study of the influence of non-adiabaticity and magnetic impurities on the value of the isotope coefficient (IC). We focus on the combined effect of these factors and examine how their relative weight affects the IC. The isotope effect of the superconducting critical temperature T-c, and of the penetration depth delta are discussed. It is shown that both non-adiabaticity and magnetic impurities have to be taken into account to describe the oxygen isotope effect of Pr-doped and oxygen-depleted YBa2Cu3O7-delta (YBCO). The calculations suggest that the effect of magnetic impurities is stronger for Pr-doped than for O-depleted YBCO. We also present new results for the IC of delta in O-depleted YBCO.