RESISTANCE ANISOTROPY IN STRONGLY ANISOTROPIC HIGH-T-C SUPERCONDUCTORS

Non-superconducting metallic single crystals from the n-type high-T-c system Pr2-xCexCuO4 exhibit a two-dimensional weak-localization behavi or at low temperatures. We use the negative magnetoresistance from the coherent backscattering of electrons in the CuO2 planes as a probe fo r the microscopic current paths, when the macroscopic current directio n is along the c-axis. The anisotropy of the magnetoresistance for the magnetic field parallel and perpendicular to the CuO2 planes provides clear evidence that the voltage drop develops mainly in the (ab) plan es. Hence metallic bridging defects between the CuO2 layers are of dom inant importance for the c-axis conductivity. We demonstrate that the peculiar anisotropy of rho(c)(T, H) at the superconducting transition of Bi(2212) crystals can be explained following the same lines.