PHOTOEXCITATION AND OXYGEN ORDERING IN YBA2CU3OX FILMS

We report on the photoinduced enhancement of the critical temperature delta T-c and the in-plane conductivity delta sigma(ab) measured in a c-axis-oriented YBa2Cu3Ox film as a function of oxygen concentration ( 6.4 less than or equal to x less than or equal to 7). Both delta T-c a nd delta sigma(ab) decrease with the oxygen content, display a plateau like behavior for 6.6 less than or equal to x less than or equal to 6. 75, and become zero at x = 7. This dependence of delta T-c on x is sim ilar to that observed for the T-c enhancement due to ordering effects in oxygen-deficient YBa2Cu3Ox single crystals. We propose that the per sistent photoinduced changes in YBa2Cu3Ox films are due to photoassist ed oxygen ordering.