Anisotropic critical current density in superconducting Bi2Sr2CaCu2O8 crystals

Critical current densities and resistivities were measured in a single crystal of the high Tc superconductor Bi2Sr2CaCu2O8 within the ab basal plane (∥) and along the c direction (⊥). A large anisotropy in critical current density is found, Jc∥/Jc⊥≊103, in quantitative agreement with the large normal-state resistivity anisotropy near Tc. The data provide strong evidence for a two-dimensional layered structure of metallic planes separated by semi-insulating barriers.