HIGH-FIELD TEMPERATURE-DEPENDENT TRANSPORT IN POLYCRYSTALLINE TL-BA-CA-CU-O

A phenomenology describing transport measurements in Bi-Sr-Ca-Cu-O is employed to describe high-field resistivity data on polycrystalline Tl-Ba-Ca-Cu-O. The data are also compared to the thermally activated flux-flow model given by Krause et al. (Physica C 205 (1993) 99) in which the activation energy was found to scale as U is-proportional-to (H cos theta)-alpha with alpha almost-equal-to 1/3. The thallium data, taken with H parallel-to J, show no evidence for conventional flux flow which varies as B/H(c2), or for thermally activated flux flow; the model presented features phase slip in a network of Josephson junctions. The resistivity is seen to vary as rho(ps)(B, T, theta) = rho(n)/[I0(gamma(beta)(B, T, theta)/2)]2 with beta = 1/3 and gamma almost-equal-to A(T)T(c)/(TB\cos(theta)\). The field-dependent polycrystalline resistivity data are dominated by crystallites with theta is-approximately-to 0 relative to the field direction. The 1/3 power is characteristic of a one-dimensional energy barrier.