Photoinduced changes in the transport properties of oxygen-deficient ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{\mathit{x}}$

We show that illumination of oxygen-deficient metallic ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{\mathit{x}}$ films produces a change in the Hall coefficient, an increase in the critical temperature, and a decrease in the electrical resistivity. These changes relax to equilibrium with characteristic times of the order of days, and are due to variations in both the carrier density and mobility. The relaxation times are of the same order of magnitude as the ones measured in nonilluminated oxygen-deficient films immediately after quenching.