The structure-induced abnormal critical current characteristics of vortex line in Bi2212 whisker

The current-voltage characteristics in different magnetic fields are measur ed on a whisker (2 mm x 0.037 mm x 0.007 mm) of highly anisotropic material Bi2212 with field H parallel to c-axis and H parallel to b-axis, respectiv ely. When H parallel to c-axis, the j(c) versus T relation remains normal f or all fields. However, when the field H is along the b-axis, we obtained a n abnormal j(c) versus T relation with a peak value appearing at T = 25 K i n H = 4 T. The possible explanations are discussed. (C) 2000 Elsevier Scien ce B.V. Ail rights reserved.