DEFECT MECHANISM OF PHOTOINDUCED SUPERCONDUCTIVITY IN YBA2CU3O6+X

Although persistent photoconductivity and photoinduced superconductivi ty have been experimentally observed in oxygen-deficient and supercond ucting YBa2Cu3O6+x, the mechanism which is responsible for these effec ts is still under debate. The possibility of a defect related mechanis m in laser-deposited thin films of YBa2Cu3O6+x is studied using four-p oint resistivity and photoluminescence techniques. It is found that th ere is a correlation between the photoluminescence spectrum and the wa velength dependence of the photoinduced conductivity. Peaks in the lum inescence spectrum change intensity upon initiation of the photoinduce d state. These results support an oxygen vacancy defect model of photo induced persistent conductivity and superconductivity in which the oxy gen vacancies act as weakly luminescent F-centers under illumination.