ANISOTROPY OF THE CRITICAL CURRENT DENSITY IN HIGH QUALITY YBa_2Cu_3O_(7-δ) THIN FILM

摘要

We have investigated the transport critical current density J_c as a function of the angle θ between the crystallographic c-axis and the applied magnetic field in high quality YBa_2Cu_3O_(7-δ) thin film. Measurements were performed for various temperature and magnetic field values. Our results show that the critical current density maximum occurs when the applied magnetic field is parallel to the ab planes (θ = 90°).The angular dependence of the critical current density shows the existence of the intrinsic pinning between the CuO_2 layers for H parallel to the ab planes and the extrinsic pinning in the configuration where the magnetic field is parallel to the c-axis. We have analyzed our results in the framework of the intrinsic pinning model proposed by Tachiki and Takahachi.