MAGNETIZATION MEASUREMENTS OF HIGH Tc SUPERCONDUCTING Ba-Y-Cu-O SYSTEM

The magnetization M(T)at a fixed field,the magnetization M(H)at different temperatures of the Ba-Y-Cu-O samples with zero resistance at 91.5K have been measured.The results show that Ba-Y-Cu-O is a type-II superconductor.We also present the anomaly of M(T)at low temperature.At T approaching OK,M(H)changes from negative to positive.The relationship between the area of magnetic hysteresis loop and the critical current density is discussed.