M. Kiuchi et al., SCALING OF CURRENT-VOLTAGE CURVES IN SUPERCONDUCTING BI-2223 SILVER-SHEATHED TAPE WIRES, Physica. C, Superconductivity, 278(1-2), 1997, pp. 62-70
The current-voltage characteristics are measured for two Bi-2223 tape
specimens with different critical current densities at various tempera
tures under the magnetic field parallel to the c-axis. It is found tha
t the current-voltage curves are scaled on two master curves by normal
izing as predicted in the vortex glass-liquid transition theory. Howev
er, the obtained dynamic critical indices increased, and the static cr
itical indices decreased appreciably with increasing magnetic field. T
hese experimental results are compared with the numerical calculation
based on the flux creep and flow model, taking the distribution of the
flux pinning strength into account. Agreement is obtained between the
experimental and theoretical results not only on the scaling curve bu
t also on the critical indices and the transition line. The static cri
tical index showing a divergence of the correlation length near the tr
ansition temperature can also be explained from the temperature depend
ence of the pinning correlation length. These results suggest that the
scaling behavior is not correlated to the phase transition of fluxoid
s assumed in the vortex glass-liquid transition theory but seems to be
correlated to a kind of transition governed by the flux pinning. (C)
1997 Elsevier Science B.V.