HYSTERESIS IN THE J(C)(B(A)) DEPENDENCE OF (BI-PB)-SR-CA-CU-O POLYCRYSTALLINE SUPERCONDUCTORS

The hysteretic behavior in the J(c)(B(a)) dependence for (Bi1.64Pb0.36 )Sr2Ca2Cu3Oy polycrystalline samples at low magnetic fields (B(a) < 30 mT) has been studied in detail. The standard four-probe technique was used to measure the critical current density. It was shown that the s amples exhibit values of J(c) (77 K) ranging from 100 to 400 A/cm2. In all the cases, a special behavior of the J(c) (B(a)) dependence in de creasing magnetic fields was observed as compared with the Y-Ba-Cu-O s ystem. An alternative explanation is given using models based on intra granular flux trapping.