Anisotropy of Bi-2212 superconducting crystals

DC magnetization of a targe high-quality Bi-2212 single crystal with a size of 5 x 5.5 x 1.3 mm(3) has been investigated in magnetic fields up to 7 T. The anisotropy of the single crystal has been studied by using a SQUID magnetometer equipped with a sample rotation system having an angle adjustment accuracy at 0.1 degrees when the magnetic field was applied at different angles between 0 degrees to 90 degrees with respect to the crystallographic a-axis of the crystal. The irreversibility line for magnetic field applied along the a-axis of the crystal was found to be located in much higher fields than those predicted by an anisotropic scaling approach. The results indicate that the anisotropy parameter gamma for this material may be as large as 1300.