Very Large Purely Intralayer Critical Current Density in Ultrathin Cuprate Artificial Structures

Ultrathin artificial high temperature superconducting structures, consisting of (Ba0.9Nd0.1)CuO₂₊ₓ and CaCuO₂ layers, were grown by pulsed laser deposition. Intralayer superconductivity at 60 K was obtained for a structure consisting of a single (CaCuO₂) block sandwiched between two (Ba0.9Nd0.1)CuO₂₊ₓ charge reservoir blocks. The purely intralayer critical current density was measured at 4.2 K and resulted to be larger than 10⁸ A/cm². These findings clearly show that interaction between nearest neighbor (CaCuO₂) layers is not essential for high Tc superconductivity and strongly supports the physical model based on the idea that intralayer interaction alone is responsible for high temperature superconductivity.