Photoinduced enhancement of superconductivity

We show clear and conclusive experimental evidence for the enhancement of superconductivity in GdBa₂Cu₃O_x and YBa₂Cu₃O_x thin films by photoexcitation. Upon laser illumination the critical temperature increases while the resistivity of the material decreases. The relaxation back to the original state is very slow, of the order of days at room temperature. The existence of this effect opens the possibility of fabricating weak-link devices with in situ tunable superconducting characteristics.