Normal-state resistivity versus critical current in YBa sub(2)Cu sub(3)O sub(7- delta ) thin films at high current densities

We report measurements at zero applied magnetic field of the normal state resistivity against temperature, rho (T), and of the characteristic curves (E-J) in YBa sub(2)Cu sub(3)O sub(7- delta ) thin films. The E-J curves are measured at different temperatures, between 77 K and the superconducting transition temperature, and up to current densities one order of magnitude larger than the critical current density, J sub(c) with the samples submerged in a liquid nitrogen bath, controlled in temperature by its vapor pressure. These E-J curves allow us to observe the abrupt electric-field jump from the superconducting state to an ohmic highly dissipative state appearing at a current density J* > > J sub(c). Our results confirm the absence of any scaling between rho and J sub(c) for thin films having different structural quality. In contrast, we have found that J* scales with the slope of the E-J curves, rho sub(n)(=E/J), for J > J*, which is very close to the extrapolation of the normal-state resistivity to the range of temperatures where the E-J curves are measured. copyright 2002 Elsevier Science B.V. All rights reserved.