Influence of annealing oxygen pressure on the laser-induced thermoelectric voltage effect in YBa2Cu3O7-x thin films

Abstract

The laser-induced thermoelectric voltage (LITV) signals were measured in the YBa2Cu3O7-x (YBCO) films annealed under different oxygen pressure. It was found that the detected LITV signals were enhanced 2—4 times with the increasing of annealing oxygen pressure. The effect can be explained by the dependence of thermoelectric anisotropy on the oxygen content in YBCO. When the films were illuminated by continuous lasers in the wavelength range of 473—808nm， the measured signals in the films annealed under 5000Pa oxygen pressure were larger than those in other films. Meanwhile， pulse ultraviolet laser illumination produced the largest signal in the films annealed under oxygen pressure of 105Pa. The response time of LITV signals was observed to become shorter with the increasing of annealing oxygen pressure， which was shown to have resulted from the increasing of thermal conductivity theoretically. The films annealed under 5000Pa oxygen pressure had the fastest response to the pulsed ultraviolet laser. The response time was 70ns and the rise time of 29ns was comparable to the duration of the applied laser pulse (about 28ns).