Temperature Dependence of Critical Current Density in YBa2Cu3O7-δ Thin Films

Q. Xiong；W. Y. Guan；P. H. Hor；C. W. Chu

Chinese Journal of Physics

30卷6期（1992 / 12 / 01）

851 - 859

英文

Well-oriented thin films of YBa2Cu3O7-δ (Y123) with a transition temperature (Tc) = 90 K and a critical current density (Jc) ＞ 10^6 A/cm^2 have been prepared by magnetron sputtering and laser ablation on SrTiO3 and LaAlO3 substrates. The temperature-dependence (T-dependence) of Jc has been obtained from M-H loops by the ac loss method, which greatly reduces the error due to the trapped magnetic field effect. At higher temperatures, the Jc vs T curves were found to have the form Jc α [1- (T/Tc)]^2 across a very broad temperature range. We have shown that ac loss measurement is a preferred reliable method to extract the T-dependence of Jc of thin films. Our results also demonstrate that this T-dependence of Jc does not depend on preparation technique, the shape of the sample and the substrate. It seems that the main dissipation mechanism of the best thin films is very similar to that of the weak-link dominated thin films.