Peculiarities of vortex state of Bi-2212 single crystals

A phase diagram of the vortex state of Bi-2212 single crystals in a magnetic field parallel to the (c) over cap-axis proposed under the assumption on the two-stage destruction of long-range vortex correlation in such crystals matches with the experimental results obtained by using different methods.(1-7) The intersection of the dimensional crossover line B-cr(T) with the line corresponding to violation of long-range vortex correlations in the (<(ab)over cap>)-plane makes it possible to explain the discontinuity at the critical point of the vortex lattice melting curve T-m(B). Possibilities of experimental investigation of low-temperature condensed state for B>B-cr and the temperature dependence B-cr(T) are considered. (C) 1998 American Institute of Physics.