Photo-induced increase of the superconducting coherence lengths in oxygen-deficient YBa2Cu3Ox thin films

YBa2Cu3Ox(x∼6.6) thin films were photodoped with white light at various temperatures from 70 K to 290 K. Before and after the excitation, the magnetoconductivity was measured in a magnetic field B=0.5 T, and the experimental results were fitted to the Aslamazov-Larkin theory of superconducting order-parameter fluctuations to determine the superconducting coherence lengths, ξc(0) and ξab(0). We observed that the photodoping process enhanced ξc(0) and ξab(0) and that the amount increased with the photodoping temperature increase. On the other hand, the superconducting anisotropy ξab(0)/ ξc(0) decreased with increasing temperature. The photodoping effect enhances superconducting properties of partially oxygen-deficient YBa2Cu3Ox samples and is considerably increased by high doping temperatures. (orig.)