中国物理B ›› 1994, Vol. 3 ›› Issue (12): 917-924.doi: 10.1088/1004-423X/3/12/006
闻海虎, 赵忠贤
WEN HAI-HU (闻海虎), ZHAO ZHONG-XIAN (赵忠贤)
摘要: By measuring magnetic torque moment in a field-sweeping process, the temperature and field dependence of the critical current density j (with a criterion of electric field) and the normalized relaxation rate Q = d lnj/d ln E of a YBa2Cu3O7-δ thin film were obtained. With a minimum current density (jmin = 10A·cm-2) the irreversibility lines at different sweeping rates were determined. It was found that these irreversibility lines cannot be fitted to either the melting line or the vortex-glass transition. All the data can be interpreted by the thermally-assisted-flux-flow model. Further investigation shows that, at irreversible tem-perature and field, Uc is much smaller than kBT, which indicates that the thermal depinning is the real origin of the irreversibility line.
中图分类号: (Critical currents)