Photoinduced superconductivity and structural changes in high temperature superconducting films

Abstract
The illumination of PryGd1−yBa2Cu3Ox semiconducting and superconducting thin films increases their critical temperatures and decreases their normal state resistivities if and only if the films are oxygen deficient. Moreover, these changes are enhanced near the Pr‐induced metal‐insulator transition. Light also causes a contraction of the c‐axis in YBa2Cu3Ox which is correlated with the observed photoinduced resistivity changes. These changes are similar to those observed when oxygen‐deficient YBa2Cu3Ox is enriched with oxygen or annealed at room temperature after quenching from high temperatures.