An intrinsic dissipative process in planar superconductors at zero appliedfield

The non-ohmic response of several II type planar superconductors in absence of magnetic field is examined as a function of temperature and current. Th e scaling of the R(T) data at constant current is obtained by plotting the resistance R vs. Q = [T-To(I)]/[Tm-To(I)], where To(I) and Tm are the tempe rature limits of the non-ohmic response in the R(T) dependence Such scaling is obtained in all the considered samples and it seems to be independent o n the boundary effects in granular specimens and on the interlayer coupling in multi-planar systems. Because of the variety of the examined samples th is behaviour appears to be an intrisic characteristic of planar superconduc tors. The R(Q) trend is well approximated by R=Ro exp {-b root[(1/Q)-1]} an d an interpretation based on the current assisted depairing of thermally ex cited vortex-antivortex pairs is proposed.