PHOTOINDUCED SUPERCONDUCTIVITY IN YSR(X)BA(2-X)CU3O(Y) FILMS

The effects of photoinduced hole doping on YSrxBa2-xCu3Oy thin films a re studied. Previously persistent photoinduced conductivity (PPC) and T-c enhancement have been observed in YBa2Cu3Oy with y < 7. We show th at these persistent photoinduced effects are absent in YSrxBa2-xCu3Oy films with an oxygen content y < 7 if the oxygen deficiency is caused by Sr doping, not by insufficient oxygenation. However, upon laser ill umination, substantial increase of T-c and normal state conductivity a re observed in YSrxBa2-xCu3Oy films annealed in reduced oxygen pressur e. The conductivity decreases and relaxes back to its original value a s the temperature approaches room temperature during the warm-up proce ss. The relaxation of PPC is much faster than that observed in YBa2Cu3 Oy. We attribute these differences to the smaller lattice constants of YSrxBa2-xCu3Oy.