ANOMALOUS MAGNETIZATION BEHAVIOR IN FIELD-COOLING MAGNETIZATION VERSUS TEMPERATURE CURVES IN TL-1223 AG SHEATHED SUPERCONDUCTING TAPE/

The zero-field-cooling and the field-cooling temperature dependence of magnetization for T1-1223/ Ag superconducting tape were measured by u sing SQUID magnetometer at fields varying from 5 Oe to 5 T in the temp erature range of 5-150 K. In the field-cooling curves, some anomalous behaviors, i.e., the positive Meissner effect in the curve of 5 Oe and the diamagnetic dip effect at fields up to 5 kOe, were observed. The diamagnetic dip minimum temperature shifts to the lower temperature as increasing the external field, and the relative amplitude decreases w ith increasing applied field. Moreover, the dip broadens with increasi ng applied field. The anomalous behaviors may be attributed to the flu x pinning and the flux depinning of Josephson-junction networks in the sample. The dip effect at lower fields may be ascribed to the intergr ain Josephson coupling networks, and that at higher fields may be due to the intrinsic intragrain Josephson coupling networks. (C) 1997 Amer ican Institute of Physics.