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 / T c )/ λ (0) vs . T / T c 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/λ 2 (0) which is proportional to superfluid density is reduced by factor 10 as T c is reduced to 48K. T c vs . 1/ λ 2 (0) in our result basically reproduces μSR result on bulk by Uemura et al. except the approximately 25% smaller value in 1/λ 2 (0) of film, which can be interpreted as impurity effect in a d -wave superconductor.