Transport critical current density and electrical characterization of patterned high- T c superconducting thin films prepared by metallo-organic decomposition

Resistivity and transport critical current density have been measured as a function of temperature for patterned YBa2Cu3O7−δ and Bi2Sr2CaCu2O8+δ superconducting thin films on single-crystal (100)-oriented MgO substrates. These granular superconducting films were prepared by the metallo-organic decomposition method. Transition temperatures Tc (ρ=0) are around 72 K for YBa2Cu3O7 and 82 K for Bi2Sr2CaCu2O8 films, both 1 μm in thickness. Critical current densities approaching 105 A/cm2 have been measured in the Bi2Sr2CaCu2O8 films at low temperatures. The critical current densities in YBa2Cu3O7 films are about 40 times lower than those in the Bi2Sr2CaCu2O8 films. It was found that near Tc the critical current density in both films is proportional to (Tc−T)2, in agreement with a superconductor–normal-metal– superconductor model developed by DeGennes [P. G. De Gennes, Rev. Mod. Phys. 36, 225 (1964)]. The reason for the much higher current density in the Bi2Sr2CaCu2O8 film is believed to be due to the stronger coupling between the superconducting grains.