Anisotropy Improvement of Critical Current Density in Bi-based Superconductor by Mg Impurity Doping

We investigated effects of Mg impurity doping on Bi₂Sr₂CaCu₂O_y high-temperature superconductor (Bi-2212 HTS). We used Bi-2212 HTS whisker as a sample and tried to improve its anisotropy of critical current density (J_c). For the Mg-doping, we adopted thermal diffusion process. In the process, nonsuperconducting phase is expected to appear on the surface of the whisker. From experimental results, we found that the anisotropy parameter of J_c can be improved from 13.8 to 1.89 by doping Mg impurity with 400 °C annealing.