Paraconductivity of a mesoscopic superconducting tube in the nonohmic regime

By using a generalized version of the time-dependent Ginzburg-Landau theory, we have calculated the paraconductivity, Δσ, of a superconducting mesoscopic tube beyond the conventional ohmic approximation. Among other dimensionality effects, the so-obtained paraconductivity expressions show that, close to T_c and deep inside the nonohmic region, a dimensional crossover from the one-dimensional to the two-dimensional fluctuation regimes can be induced which, in turn, may be understood in terms of an effective shrinkage of the superconducting coherence length with the electrical field. These nonohmic effects on Δσ may be observed in Al mesoscopic tubes and carbon nanotubes, thus opening new experimental possibilities to investigate the superconducting behavior of these nanostructured materials.