MAGNETIZATION MEASUREMENTS OF HIGH T_c 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.