VORTEX FLUCTUATIONS IN POLYCRYSTALLINE BI1.75PB0.25SR2CA2CU3O10

Reversible magnetization M(H, T) data are reported for polycrystalline Bi1.75Pb0.25Sr2Ca2Cu3O10. After subtraction of the normal state contribution, the data exhibit a characteristic fluctuations dominated behavior near the critical temperature, already observed experimentally and explained theoretically for single crystals of weakly coupled layered superconductors with the magnetic field along the c crystal direction. It is shown that the M(H, T) behavior is compatible with the notion that only the field component along the c-axis of each crystalline grain results in an induced superconducting state magnetization.