Nonzero resistance in the superconducting state of narrow BSCCO whiskers

Temperature dependences of the resistance and current-voltage (I-V) charact eristics for BSCCO (2212) whiskers of different width, w = 1 - 15 mu m, as well as for whiskers with width steps, are measured. Below the Berezinskii- Kosterlitz-Thouless transition, finite Ohmic resistance is found for w < 5 mu m; in contrast, for the wide whiskers we observe V proportional to Ia(T) +1 with a > 2, AS the width decreases, the resistivity of the whiskers belo w the transition temperature increases, while above the transition it decre ases. The size effects are explained by thermal generation and annihilation of two-dimensional (2D) vortices at the sample edges. At low temperatures and large currents the width of the sample does not affect considerably the shape of the I-V curves. (C) 2000 Published by Elsevier Science B.V. All r ights reserved.