Persistent Photoinduced Effects Research Articles

PERSISTENT PHOTOCONDUCTIVITY IN La0.7CaxBa1-xMnO3 THIN FILMS

We report, for the first time, experiments of persistent photoconductivity (PPC) in thin films of manganese perovskites La 0.7 Ca 0.25 Ba 0.05 MnO 3 and La 0.7 Ca 0.2 Ba 0.1 MnO 3 showing a persistent decrease of a few percent of the resistance after illumination with visible light. These persistent photoinduced effects are seen only in a range of low temperatures (<25 K) well below the insulator-metal transition at respectively T c=173 K and T c=120 K. In this low temperature range, the transport mechanism is rather of activated hopping type regime.

Persistent photoinduced effects in high‐Te superconductors

The reaction of high‐temperature cuprate superconductors to illumination differs from the reaction produced in conventional superconductors. Two such effects, reviewed here, are persistent photoconductivity and persistent photoinduced superconductivity. For example, REBa2Cu3Ox thin films show a decrease in the normal state resistance and an increase of Tc which persist for a long time at low temperatures (< 100 K). The experimental investigations and results are briefly presented, before two alternative theoretical models are considered.