MAGNETIZATION HYSTERESIS OF QUENCH-MELT-GROWTH PROCESSED YBA2CU3O7 INHIGH FIELDS UP TO 23 T

Using a newly established vibrating-sample magnetometer (VSM) combined with a hybrid magnet, the magnetic hysteresis of a quench-melt-growth processed YBa2Cu3O7 has been measured in wide temperature and field r anges (4.2 less than or equal to T < 91 K and 0 less than or equal to H < 23 T). The magnetization loops show different characteristics in d ifferent temperature regions. At high temperatures above 70 K; magneti zation curves show a normal characteristic and can be scaled using the remanent magnetization and the irreversibility field as scaling param eters. A magnetization anomaly often called the fishtail effect is obs erved only in an intermediate temperature region (typically 40 less th an or equal to T < 70 K). In this temperature region, using irreversib ility field and the peak magnetization in the fishtail effect as the s caling parameters, magnetic hysteresis is well scaled in fields up to 23 T. At low temperatures below 40 K, magnetization curves indicate a weak dependence of the critical current on fields up to 23 T. However, it is difficult for them to find the appropriate scaling parameters. The fishtail effect observed in the present experiments shows a differ ent behavior than reported so far. In particular, the peak field in th e peak effect first increased very slowly with decreasing temperature and then decreased when temperature was reduced from 50 to 40 K. The p eak effect was absent below 40 K.