Thermally activated flux creep and percolative conduction in YBa2Cu3O7-y/Ag composite thick films

Temperature-dependent electrical resistivity of a set of YBa2Cu3O7/Ag composite thick films prepared by a reaction diffusion technique was analyzed to determine activation energy. Both measurement current and magnetic field were varied to study P vs T characteristics. The applied magnetic field and the measurement current tilt the potential profile that reduces the potential barrier and enhances the vortex motion in the system. The power dependence of activation energy, U-0(H) and U-0(I) was predicted to obey the power law. From the exponents of the above form, it is observed that the effect of current is dominant over that of the applied magnetic field in reducing the activation energy. A percolative nature of current conduction is explained through the current-controlled tailing of the resistivity transition near T-c0.