Study of Resistive Superconducting Transition in YBa_2Cu_3O_7 Films(High-T_c Superconducting Materials Research)

The resistive superconducting transition of highly oriented YBa_2Cu_3O_7 films grown by chemical vapor deposition has been investigated in high magnetic fields up to 25 T. The fluctuation conductivity based on the recent scaling law of the thermodynamic fluctuation as well as the dissipation due to the thermally activated flux-line motion are discussed. The upper critical field H_ and the depinning field H^+ are obtained as a function of temperature. Behaviors of these characteristic fields and the pinning potential are also discussed