STRONG 3D CORRELATIONS IN THE VORTEX SYSTEM OF BI2212:PB

The experimental study of magnetic flux penetration under crossed magnetic fields in Bi 2212:Pb single crystals is performed by MO. A remarkable field penetration pattern alteration and superconducting current anisotropy enhancement by the in-plane field is revealed. The anisotropy increases with the temperature rise up to T m = 54 ± 2 K. The anisotropy of the flux creep rate and an asymmetry of the flux relaxation is observed at T T m. The flux penetration anisotropy is considered as an evidence for a strong 3D correlation between pancake vortices in different CuO planes at T < Tm.