The experimental study of magnetic flux penetration under crossed magnetic fields in Bi2212:Pb single crystal performed by magnetooptic technique (MO) reveals remarkable field penetration pattern alteration (flux configuration change) and superconducting current anisotropy enhancement by the in-plane field. The anisotropy increases with the temperature rise up to Tm=54±2K. At T=Tm an abrupt change in the flux behavior is found; the correlation between the in-plane magnetic field and the out-of-plane magnetic flux penetration disappears. No correlation is observed for T>Tm. The transition temperature Tm does not depend on the magnetic field strength. The observed flux penetration anisotropy is considered as an evidence of a strong 3D - correlation between pancake vortices in different CuO planes at T<Tm. This enables understanding of a remarkable pinning observed in Bi2212:Pb at low temperatures.
@article{arxiv.cond-mat/0303103,
title = {Strong 3D correlations in vortex system of Bi2212:Pb},
author = {L. S. Uspenskaya and A. B. Kulakov and A. L. Rakhmanov},
journal= {arXiv preprint arXiv:cond-mat/0303103},
year = {2009}
}