Optical and electrical enhancement of flux creep in YBa2Cu3O7-epitaxial films

Abstract

We report two novel flux-creep-related phenomena in YBa2Cu3O7-films at elevated currents in presence of magnetic fields: a sharp onset of nonequilibrium optical response and a current-dependent thermally activated electrical resistivity. In this regime the activation energy of the resistivity scales uniquely with current density as log(J0/J) with J03×106 A/Cm2. This nonlinear current dependence is significantly different from the predictions of the standard flux-creep model. At currents 7×103 A/cm2 the resistivity is current independent and the optical response is purely bolometric. © 1989 The American Physical Society.