Low-field irreversibility line and its anisotropy of textured (Bi,Pb)2Sr2Ca2Cu3Oy silver-clad tapes

The irreversibility line H-irr(T) of textured (Bi,Pb)(2)Sr2Ca2Cu3Oy silver-clad tapes was obtained by ac susceptibility (ACS) and magnetoresistivity (MR) below 1500 G. It is found that, in the framework of flux motion, the H-irr(T) is determined by the thermally activated flux flow (TAFF) rather than the so-called giant flux creep, and the experimentally obtained H-irr(T) line is related to a certain resistivity criterion in both ACS and resistivity measurements. H-irr(T) is found to be significantly depressed by the amplitude of applied driving AC field and generally lower than that measured from the resistivity. The anisotropy in H-irr(T) is found to follow a scaling behaviour as described by the anisotropic effective mass model. (C) 1999 Published by Elsevier Science B.V. All rights reserved.