Irreversibility lines and pinning force density of aligned (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ single crystals

DC magnetic properties of aligned (Bi,Pb)/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub x/ single crystals have been measured for the first time using a SQUID magnetometer in field up to 5 T and in the temperature range from 5 K to 150 K. The results confirm the existence of a broad temperature and field regime with completely reversible magnetization for these crystals. The temperature dependence of the irreversibility field H*(T) is determined from both M-H and M-T curves with fields oriented perpendicular to the ab plane of the crystal lattice. A strong field dependence of critical current density has been observed in these pristine single crystals with very weak pinning. These observations emphasize the importance of artificially introducing pinning sites in BSCCO material used for applications. Non-linear scaling models have been used to fit our experimental results to estimate the elemental pinning force density and the effective pinning potential.