Thermal effects in the flux-creep regime of YBa2Cu3O7-δ thin film microbridges under high current densities in self field

Abstract

currents well above the critical current density Jc but below the quenching current density J* (the current inducing the full transition to the normal state), the electric field vs current density (E-J) curves may be deeply affected by self-heating effects. Until now the influence of these thermal effects on the E-J curves was mainly studied around J*. Here we will first present measurements of the E-J curves in several YBa2Cu3O7-δ thin film microbridges in the whole range between Jc and J*. Our results confirm that whereas Jc is almost independent on the microbridge width (w), J* and E* strongly increase when the width decreases. It is also shown that the width dependence on the E-J curves manifests itself already for current densities well below J*(w). Then by using a finite-element method (FEM), it is shown that the measured E-J curves may be explained, from the dissipation onset (Jc) up to the jump itself (J*), in terms of a conventional (smooth) flux-creep plus self-heating effects. An important aspect of our results is that the same flux-creep behaviour in the low dissipation regime allows us to explain the whole E-J curves in film microbridges with different widths.