Pinning Centers and Thermally Activated Flux Flow in GdBa2Cu3O7–δ Superconducting Film

Gd₁Ba₂Cu₃O_7–δ/SrTiO₃ (Gd123/STO) superconductor film (~ 200 nm) was prepared using pulsed laser deposition technique. X-ray diffraction pattern of film reveals the polycrystalline growth with the lattice mismatch ~ 0.25% between the film and substrate. From the resistive behavior, it is clear that Gd123 film exhibits T_C^onset ~ 89 K and T_{CR = 0} ~ 78 K while mean field T_C is ~ 83 K. Temperature dependent resistivity (2–150 K) studies in various applied magnetic fields have been understood on the basis of thermally activated flux flow mechanism. It is observed that the pinning energy decreases with increase in applied magnetic field. To understand the transport mechanism and field effect of magnetic field on the conduction in normal state of film, all the resistivity plots were fitted, where power law is found to increase with increase in applied magnetic field which indicates the field induced enhancement in the inter-band charge carrier scattering in Gd123 film.