Penetration depth in oxygen depleted YBCO thin films

The effect of oxygen depletion on YBCO film is investigated via penetration depth measurements. The T-dependence is measured in high precision for each oxygen concentration. λ(T/Tc)/λ(0) vs. T/Tc for our films is almost identical for different oxygen content. For a fully oxygenated film, it agrees extremely well with the crystal data for T > 25K. 1/λ2(0) which is proportional to superfluid density is reduced by factor 10 as Tc is reduced to 48K. Tc vs. 1/λ2(0) in our result basically reproduces μSR result on bulk by Uemura et al. except the approximately 25% smaller value in 1/λ2(0) of film, which can be interpreted as impurity effect in a d-wave superconductor.