FLUX CREEP AND CURRENT RELAXATION UP TO TC IN BI2SR2CACU2OY SINGLE-CRYSTALS

The drastic change of the vortex structure dynamics at T(j) congruent-to 17 K, characterized by the sharp ten-fold drop of the normalized relaxation rate S = -(M0(-1))partial derivative M/partial derivative ln t, by the change of the "magnetic" critical current temperature dependence, and by the change of the exponent in the relaxation rate vs. persistent current dependence as well, - is observed in the Bi-2212 single crystal. It is shown that at T --> T(c) the activation energy U0 = T/S doesn't drop. Results are explained in the framework of the expanded Anderson model; the attempt time tau-0 approximately (1 divided-by 10)sec is deduced.